| /* |
| * Copyright (c) 2008, 2017, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle in the LICENSE file that accompanied this code. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| package java.lang.invoke; |
| |
| import sun.invoke.util.VerifyAccess; |
| import sun.invoke.util.Wrapper; |
| import sun.reflect.Reflection; |
| |
| import java.lang.reflect.*; |
| import java.nio.ByteOrder; |
| import java.util.List; |
| import java.util.Arrays; |
| import java.util.ArrayList; |
| import java.util.Iterator; |
| import java.util.NoSuchElementException; |
| import java.util.Objects; |
| import java.util.stream.Collectors; |
| import java.util.stream.Stream; |
| |
| import static java.lang.invoke.MethodHandleStatics.*; |
| import static java.lang.invoke.MethodHandleStatics.newIllegalArgumentException; |
| import static java.lang.invoke.MethodType.methodType; |
| |
| /** |
| * This class consists exclusively of static methods that operate on or return |
| * method handles. They fall into several categories: |
| * <ul> |
| * <li>Lookup methods which help create method handles for methods and fields. |
| * <li>Combinator methods, which combine or transform pre-existing method handles into new ones. |
| * <li>Other factory methods to create method handles that emulate other common JVM operations or control flow patterns. |
| * </ul> |
| * <p> |
| * @author John Rose, JSR 292 EG |
| * @since 1.7 |
| */ |
| public class MethodHandles { |
| |
| private MethodHandles() { } // do not instantiate |
| |
| // Android-changed: We do not use MemberName / MethodHandleImpl. |
| // |
| // private static final MemberName.Factory IMPL_NAMES = MemberName.getFactory(); |
| // static { MethodHandleImpl.initStatics(); } |
| // See IMPL_LOOKUP below. |
| |
| //// Method handle creation from ordinary methods. |
| |
| /** |
| * Returns a {@link Lookup lookup object} with |
| * full capabilities to emulate all supported bytecode behaviors of the caller. |
| * These capabilities include <a href="MethodHandles.Lookup.html#privacc">private access</a> to the caller. |
| * Factory methods on the lookup object can create |
| * <a href="MethodHandleInfo.html#directmh">direct method handles</a> |
| * for any member that the caller has access to via bytecodes, |
| * including protected and private fields and methods. |
| * This lookup object is a <em>capability</em> which may be delegated to trusted agents. |
| * Do not store it in place where untrusted code can access it. |
| * <p> |
| * This method is caller sensitive, which means that it may return different |
| * values to different callers. |
| * <p> |
| * For any given caller class {@code C}, the lookup object returned by this call |
| * has equivalent capabilities to any lookup object |
| * supplied by the JVM to the bootstrap method of an |
| * <a href="package-summary.html#indyinsn">invokedynamic instruction</a> |
| * executing in the same caller class {@code C}. |
| * @return a lookup object for the caller of this method, with private access |
| */ |
| // Android-changed: Remove caller sensitive. |
| // @CallerSensitive |
| public static Lookup lookup() { |
| return new Lookup(Reflection.getCallerClass()); |
| } |
| |
| /** |
| * Returns a {@link Lookup lookup object} which is trusted minimally. |
| * It can only be used to create method handles to |
| * publicly accessible fields and methods. |
| * <p> |
| * As a matter of pure convention, the {@linkplain Lookup#lookupClass lookup class} |
| * of this lookup object will be {@link java.lang.Object}. |
| * |
| * <p style="font-size:smaller;"> |
| * <em>Discussion:</em> |
| * The lookup class can be changed to any other class {@code C} using an expression of the form |
| * {@link Lookup#in publicLookup().in(C.class)}. |
| * Since all classes have equal access to public names, |
| * such a change would confer no new access rights. |
| * A public lookup object is always subject to |
| * <a href="MethodHandles.Lookup.html#secmgr">security manager checks</a>. |
| * Also, it cannot access |
| * <a href="MethodHandles.Lookup.html#callsens">caller sensitive methods</a>. |
| * @return a lookup object which is trusted minimally |
| */ |
| public static Lookup publicLookup() { |
| return Lookup.PUBLIC_LOOKUP; |
| } |
| |
| // Android-removed: Documentation related to the security manager and module checks |
| /** |
| * Returns a {@link Lookup lookup object} with full capabilities to emulate all |
| * supported bytecode behaviors, including <a href="MethodHandles.Lookup.html#privacc"> |
| * private access</a>, on a target class. |
| * @param targetClass the target class |
| * @param lookup the caller lookup object |
| * @return a lookup object for the target class, with private access |
| * @throws IllegalArgumentException if {@code targetClass} is a primitive type or array class |
| * @throws NullPointerException if {@code targetClass} or {@code caller} is {@code null} |
| * @throws IllegalAccessException is not thrown on Android |
| * @since 9 |
| */ |
| public static Lookup privateLookupIn(Class<?> targetClass, Lookup lookup) throws IllegalAccessException { |
| // Android-removed: SecurityManager calls |
| // SecurityManager sm = System.getSecurityManager(); |
| // if (sm != null) sm.checkPermission(ACCESS_PERMISSION); |
| if (targetClass.isPrimitive()) |
| throw new IllegalArgumentException(targetClass + " is a primitive class"); |
| if (targetClass.isArray()) |
| throw new IllegalArgumentException(targetClass + " is an array class"); |
| // BEGIN Android-removed: There is no module information on Android |
| /** |
| * Module targetModule = targetClass.getModule(); |
| * Module callerModule = lookup.lookupClass().getModule(); |
| * if (!callerModule.canRead(targetModule)) |
| * throw new IllegalAccessException(callerModule + " does not read " + targetModule); |
| * if (targetModule.isNamed()) { |
| * String pn = targetClass.getPackageName(); |
| * assert pn.length() > 0 : "unnamed package cannot be in named module"; |
| * if (!targetModule.isOpen(pn, callerModule)) |
| * throw new IllegalAccessException(targetModule + " does not open " + pn + " to " + callerModule); |
| * } |
| * if ((lookup.lookupModes() & Lookup.MODULE) == 0) |
| * throw new IllegalAccessException("lookup does not have MODULE lookup mode"); |
| * if (!callerModule.isNamed() && targetModule.isNamed()) { |
| * IllegalAccessLogger logger = IllegalAccessLogger.illegalAccessLogger(); |
| * if (logger != null) { |
| * logger.logIfOpenedForIllegalAccess(lookup, targetClass); |
| * } |
| * } |
| */ |
| // END Android-removed: There is no module information on Android |
| return new Lookup(targetClass); |
| } |
| |
| |
| /** |
| * Performs an unchecked "crack" of a |
| * <a href="MethodHandleInfo.html#directmh">direct method handle</a>. |
| * The result is as if the user had obtained a lookup object capable enough |
| * to crack the target method handle, called |
| * {@link java.lang.invoke.MethodHandles.Lookup#revealDirect Lookup.revealDirect} |
| * on the target to obtain its symbolic reference, and then called |
| * {@link java.lang.invoke.MethodHandleInfo#reflectAs MethodHandleInfo.reflectAs} |
| * to resolve the symbolic reference to a member. |
| * <p> |
| * If there is a security manager, its {@code checkPermission} method |
| * is called with a {@code ReflectPermission("suppressAccessChecks")} permission. |
| * @param <T> the desired type of the result, either {@link Member} or a subtype |
| * @param target a direct method handle to crack into symbolic reference components |
| * @param expected a class object representing the desired result type {@code T} |
| * @return a reference to the method, constructor, or field object |
| * @exception SecurityException if the caller is not privileged to call {@code setAccessible} |
| * @exception NullPointerException if either argument is {@code null} |
| * @exception IllegalArgumentException if the target is not a direct method handle |
| * @exception ClassCastException if the member is not of the expected type |
| * @since 1.8 |
| */ |
| public static <T extends Member> T |
| reflectAs(Class<T> expected, MethodHandle target) { |
| MethodHandleImpl directTarget = getMethodHandleImpl(target); |
| // Given that this is specified to be an "unchecked" crack, we can directly allocate |
| // a member from the underlying ArtField / Method and bypass all associated access checks. |
| return expected.cast(directTarget.getMemberInternal()); |
| } |
| |
| /** |
| * A <em>lookup object</em> is a factory for creating method handles, |
| * when the creation requires access checking. |
| * Method handles do not perform |
| * access checks when they are called, but rather when they are created. |
| * Therefore, method handle access |
| * restrictions must be enforced when a method handle is created. |
| * The caller class against which those restrictions are enforced |
| * is known as the {@linkplain #lookupClass lookup class}. |
| * <p> |
| * A lookup class which needs to create method handles will call |
| * {@link #lookup MethodHandles.lookup} to create a factory for itself. |
| * When the {@code Lookup} factory object is created, the identity of the lookup class is |
| * determined, and securely stored in the {@code Lookup} object. |
| * The lookup class (or its delegates) may then use factory methods |
| * on the {@code Lookup} object to create method handles for access-checked members. |
| * This includes all methods, constructors, and fields which are allowed to the lookup class, |
| * even private ones. |
| * |
| * <h1><a name="lookups"></a>Lookup Factory Methods</h1> |
| * The factory methods on a {@code Lookup} object correspond to all major |
| * use cases for methods, constructors, and fields. |
| * Each method handle created by a factory method is the functional |
| * equivalent of a particular <em>bytecode behavior</em>. |
| * (Bytecode behaviors are described in section 5.4.3.5 of the Java Virtual Machine Specification.) |
| * Here is a summary of the correspondence between these factory methods and |
| * the behavior the resulting method handles: |
| * <table border=1 cellpadding=5 summary="lookup method behaviors"> |
| * <tr> |
| * <th><a name="equiv"></a>lookup expression</th> |
| * <th>member</th> |
| * <th>bytecode behavior</th> |
| * </tr> |
| * <tr> |
| * <td>{@link java.lang.invoke.MethodHandles.Lookup#findGetter lookup.findGetter(C.class,"f",FT.class)}</td> |
| * <td>{@code FT f;}</td><td>{@code (T) this.f;}</td> |
| * </tr> |
| * <tr> |
| * <td>{@link java.lang.invoke.MethodHandles.Lookup#findStaticGetter lookup.findStaticGetter(C.class,"f",FT.class)}</td> |
| * <td>{@code static}<br>{@code FT f;}</td><td>{@code (T) C.f;}</td> |
| * </tr> |
| * <tr> |
| * <td>{@link java.lang.invoke.MethodHandles.Lookup#findSetter lookup.findSetter(C.class,"f",FT.class)}</td> |
| * <td>{@code FT f;}</td><td>{@code this.f = x;}</td> |
| * </tr> |
| * <tr> |
| * <td>{@link java.lang.invoke.MethodHandles.Lookup#findStaticSetter lookup.findStaticSetter(C.class,"f",FT.class)}</td> |
| * <td>{@code static}<br>{@code FT f;}</td><td>{@code C.f = arg;}</td> |
| * </tr> |
| * <tr> |
| * <td>{@link java.lang.invoke.MethodHandles.Lookup#findVirtual lookup.findVirtual(C.class,"m",MT)}</td> |
| * <td>{@code T m(A*);}</td><td>{@code (T) this.m(arg*);}</td> |
| * </tr> |
| * <tr> |
| * <td>{@link java.lang.invoke.MethodHandles.Lookup#findStatic lookup.findStatic(C.class,"m",MT)}</td> |
| * <td>{@code static}<br>{@code T m(A*);}</td><td>{@code (T) C.m(arg*);}</td> |
| * </tr> |
| * <tr> |
| * <td>{@link java.lang.invoke.MethodHandles.Lookup#findSpecial lookup.findSpecial(C.class,"m",MT,this.class)}</td> |
| * <td>{@code T m(A*);}</td><td>{@code (T) super.m(arg*);}</td> |
| * </tr> |
| * <tr> |
| * <td>{@link java.lang.invoke.MethodHandles.Lookup#findConstructor lookup.findConstructor(C.class,MT)}</td> |
| * <td>{@code C(A*);}</td><td>{@code new C(arg*);}</td> |
| * </tr> |
| * <tr> |
| * <td>{@link java.lang.invoke.MethodHandles.Lookup#unreflectGetter lookup.unreflectGetter(aField)}</td> |
| * <td>({@code static})?<br>{@code FT f;}</td><td>{@code (FT) aField.get(thisOrNull);}</td> |
| * </tr> |
| * <tr> |
| * <td>{@link java.lang.invoke.MethodHandles.Lookup#unreflectSetter lookup.unreflectSetter(aField)}</td> |
| * <td>({@code static})?<br>{@code FT f;}</td><td>{@code aField.set(thisOrNull, arg);}</td> |
| * </tr> |
| * <tr> |
| * <td>{@link java.lang.invoke.MethodHandles.Lookup#unreflect lookup.unreflect(aMethod)}</td> |
| * <td>({@code static})?<br>{@code T m(A*);}</td><td>{@code (T) aMethod.invoke(thisOrNull, arg*);}</td> |
| * </tr> |
| * <tr> |
| * <td>{@link java.lang.invoke.MethodHandles.Lookup#unreflectConstructor lookup.unreflectConstructor(aConstructor)}</td> |
| * <td>{@code C(A*);}</td><td>{@code (C) aConstructor.newInstance(arg*);}</td> |
| * </tr> |
| * <tr> |
| * <td>{@link java.lang.invoke.MethodHandles.Lookup#unreflect lookup.unreflect(aMethod)}</td> |
| * <td>({@code static})?<br>{@code T m(A*);}</td><td>{@code (T) aMethod.invoke(thisOrNull, arg*);}</td> |
| * </tr> |
| * </table> |
| * |
| * Here, the type {@code C} is the class or interface being searched for a member, |
| * documented as a parameter named {@code refc} in the lookup methods. |
| * The method type {@code MT} is composed from the return type {@code T} |
| * and the sequence of argument types {@code A*}. |
| * The constructor also has a sequence of argument types {@code A*} and |
| * is deemed to return the newly-created object of type {@code C}. |
| * Both {@code MT} and the field type {@code FT} are documented as a parameter named {@code type}. |
| * The formal parameter {@code this} stands for the self-reference of type {@code C}; |
| * if it is present, it is always the leading argument to the method handle invocation. |
| * (In the case of some {@code protected} members, {@code this} may be |
| * restricted in type to the lookup class; see below.) |
| * The name {@code arg} stands for all the other method handle arguments. |
| * In the code examples for the Core Reflection API, the name {@code thisOrNull} |
| * stands for a null reference if the accessed method or field is static, |
| * and {@code this} otherwise. |
| * The names {@code aMethod}, {@code aField}, and {@code aConstructor} stand |
| * for reflective objects corresponding to the given members. |
| * <p> |
| * In cases where the given member is of variable arity (i.e., a method or constructor) |
| * the returned method handle will also be of {@linkplain MethodHandle#asVarargsCollector variable arity}. |
| * In all other cases, the returned method handle will be of fixed arity. |
| * <p style="font-size:smaller;"> |
| * <em>Discussion:</em> |
| * The equivalence between looked-up method handles and underlying |
| * class members and bytecode behaviors |
| * can break down in a few ways: |
| * <ul style="font-size:smaller;"> |
| * <li>If {@code C} is not symbolically accessible from the lookup class's loader, |
| * the lookup can still succeed, even when there is no equivalent |
| * Java expression or bytecoded constant. |
| * <li>Likewise, if {@code T} or {@code MT} |
| * is not symbolically accessible from the lookup class's loader, |
| * the lookup can still succeed. |
| * For example, lookups for {@code MethodHandle.invokeExact} and |
| * {@code MethodHandle.invoke} will always succeed, regardless of requested type. |
| * <li>If there is a security manager installed, it can forbid the lookup |
| * on various grounds (<a href="MethodHandles.Lookup.html#secmgr">see below</a>). |
| * By contrast, the {@code ldc} instruction on a {@code CONSTANT_MethodHandle} |
| * constant is not subject to security manager checks. |
| * <li>If the looked-up method has a |
| * <a href="MethodHandle.html#maxarity">very large arity</a>, |
| * the method handle creation may fail, due to the method handle |
| * type having too many parameters. |
| * </ul> |
| * |
| * <h1><a name="access"></a>Access checking</h1> |
| * Access checks are applied in the factory methods of {@code Lookup}, |
| * when a method handle is created. |
| * This is a key difference from the Core Reflection API, since |
| * {@link java.lang.reflect.Method#invoke java.lang.reflect.Method.invoke} |
| * performs access checking against every caller, on every call. |
| * <p> |
| * All access checks start from a {@code Lookup} object, which |
| * compares its recorded lookup class against all requests to |
| * create method handles. |
| * A single {@code Lookup} object can be used to create any number |
| * of access-checked method handles, all checked against a single |
| * lookup class. |
| * <p> |
| * A {@code Lookup} object can be shared with other trusted code, |
| * such as a metaobject protocol. |
| * A shared {@code Lookup} object delegates the capability |
| * to create method handles on private members of the lookup class. |
| * Even if privileged code uses the {@code Lookup} object, |
| * the access checking is confined to the privileges of the |
| * original lookup class. |
| * <p> |
| * A lookup can fail, because |
| * the containing class is not accessible to the lookup class, or |
| * because the desired class member is missing, or because the |
| * desired class member is not accessible to the lookup class, or |
| * because the lookup object is not trusted enough to access the member. |
| * In any of these cases, a {@code ReflectiveOperationException} will be |
| * thrown from the attempted lookup. The exact class will be one of |
| * the following: |
| * <ul> |
| * <li>NoSuchMethodException — if a method is requested but does not exist |
| * <li>NoSuchFieldException — if a field is requested but does not exist |
| * <li>IllegalAccessException — if the member exists but an access check fails |
| * </ul> |
| * <p> |
| * In general, the conditions under which a method handle may be |
| * looked up for a method {@code M} are no more restrictive than the conditions |
| * under which the lookup class could have compiled, verified, and resolved a call to {@code M}. |
| * Where the JVM would raise exceptions like {@code NoSuchMethodError}, |
| * a method handle lookup will generally raise a corresponding |
| * checked exception, such as {@code NoSuchMethodException}. |
| * And the effect of invoking the method handle resulting from the lookup |
| * is <a href="MethodHandles.Lookup.html#equiv">exactly equivalent</a> |
| * to executing the compiled, verified, and resolved call to {@code M}. |
| * The same point is true of fields and constructors. |
| * <p style="font-size:smaller;"> |
| * <em>Discussion:</em> |
| * Access checks only apply to named and reflected methods, |
| * constructors, and fields. |
| * Other method handle creation methods, such as |
| * {@link MethodHandle#asType MethodHandle.asType}, |
| * do not require any access checks, and are used |
| * independently of any {@code Lookup} object. |
| * <p> |
| * If the desired member is {@code protected}, the usual JVM rules apply, |
| * including the requirement that the lookup class must be either be in the |
| * same package as the desired member, or must inherit that member. |
| * (See the Java Virtual Machine Specification, sections 4.9.2, 5.4.3.5, and 6.4.) |
| * In addition, if the desired member is a non-static field or method |
| * in a different package, the resulting method handle may only be applied |
| * to objects of the lookup class or one of its subclasses. |
| * This requirement is enforced by narrowing the type of the leading |
| * {@code this} parameter from {@code C} |
| * (which will necessarily be a superclass of the lookup class) |
| * to the lookup class itself. |
| * <p> |
| * The JVM imposes a similar requirement on {@code invokespecial} instruction, |
| * that the receiver argument must match both the resolved method <em>and</em> |
| * the current class. Again, this requirement is enforced by narrowing the |
| * type of the leading parameter to the resulting method handle. |
| * (See the Java Virtual Machine Specification, section 4.10.1.9.) |
| * <p> |
| * The JVM represents constructors and static initializer blocks as internal methods |
| * with special names ({@code "<init>"} and {@code "<clinit>"}). |
| * The internal syntax of invocation instructions allows them to refer to such internal |
| * methods as if they were normal methods, but the JVM bytecode verifier rejects them. |
| * A lookup of such an internal method will produce a {@code NoSuchMethodException}. |
| * <p> |
| * In some cases, access between nested classes is obtained by the Java compiler by creating |
| * an wrapper method to access a private method of another class |
| * in the same top-level declaration. |
| * For example, a nested class {@code C.D} |
| * can access private members within other related classes such as |
| * {@code C}, {@code C.D.E}, or {@code C.B}, |
| * but the Java compiler may need to generate wrapper methods in |
| * those related classes. In such cases, a {@code Lookup} object on |
| * {@code C.E} would be unable to those private members. |
| * A workaround for this limitation is the {@link Lookup#in Lookup.in} method, |
| * which can transform a lookup on {@code C.E} into one on any of those other |
| * classes, without special elevation of privilege. |
| * <p> |
| * The accesses permitted to a given lookup object may be limited, |
| * according to its set of {@link #lookupModes lookupModes}, |
| * to a subset of members normally accessible to the lookup class. |
| * For example, the {@link #publicLookup publicLookup} |
| * method produces a lookup object which is only allowed to access |
| * public members in public classes. |
| * The caller sensitive method {@link #lookup lookup} |
| * produces a lookup object with full capabilities relative to |
| * its caller class, to emulate all supported bytecode behaviors. |
| * Also, the {@link Lookup#in Lookup.in} method may produce a lookup object |
| * with fewer access modes than the original lookup object. |
| * |
| * <p style="font-size:smaller;"> |
| * <a name="privacc"></a> |
| * <em>Discussion of private access:</em> |
| * We say that a lookup has <em>private access</em> |
| * if its {@linkplain #lookupModes lookup modes} |
| * include the possibility of accessing {@code private} members. |
| * As documented in the relevant methods elsewhere, |
| * only lookups with private access possess the following capabilities: |
| * <ul style="font-size:smaller;"> |
| * <li>access private fields, methods, and constructors of the lookup class |
| * <li>create method handles which invoke <a href="MethodHandles.Lookup.html#callsens">caller sensitive</a> methods, |
| * such as {@code Class.forName} |
| * <li>create method handles which {@link Lookup#findSpecial emulate invokespecial} instructions |
| * <li>avoid <a href="MethodHandles.Lookup.html#secmgr">package access checks</a> |
| * for classes accessible to the lookup class |
| * <li>create {@link Lookup#in delegated lookup objects} which have private access to other classes |
| * within the same package member |
| * </ul> |
| * <p style="font-size:smaller;"> |
| * Each of these permissions is a consequence of the fact that a lookup object |
| * with private access can be securely traced back to an originating class, |
| * whose <a href="MethodHandles.Lookup.html#equiv">bytecode behaviors</a> and Java language access permissions |
| * can be reliably determined and emulated by method handles. |
| * |
| * <h1><a name="secmgr"></a>Security manager interactions</h1> |
| * Although bytecode instructions can only refer to classes in |
| * a related class loader, this API can search for methods in any |
| * class, as long as a reference to its {@code Class} object is |
| * available. Such cross-loader references are also possible with the |
| * Core Reflection API, and are impossible to bytecode instructions |
| * such as {@code invokestatic} or {@code getfield}. |
| * There is a {@linkplain java.lang.SecurityManager security manager API} |
| * to allow applications to check such cross-loader references. |
| * These checks apply to both the {@code MethodHandles.Lookup} API |
| * and the Core Reflection API |
| * (as found on {@link java.lang.Class Class}). |
| * <p> |
| * If a security manager is present, member lookups are subject to |
| * additional checks. |
| * From one to three calls are made to the security manager. |
| * Any of these calls can refuse access by throwing a |
| * {@link java.lang.SecurityException SecurityException}. |
| * Define {@code smgr} as the security manager, |
| * {@code lookc} as the lookup class of the current lookup object, |
| * {@code refc} as the containing class in which the member |
| * is being sought, and {@code defc} as the class in which the |
| * member is actually defined. |
| * The value {@code lookc} is defined as <em>not present</em> |
| * if the current lookup object does not have |
| * <a href="MethodHandles.Lookup.html#privacc">private access</a>. |
| * The calls are made according to the following rules: |
| * <ul> |
| * <li><b>Step 1:</b> |
| * If {@code lookc} is not present, or if its class loader is not |
| * the same as or an ancestor of the class loader of {@code refc}, |
| * then {@link SecurityManager#checkPackageAccess |
| * smgr.checkPackageAccess(refcPkg)} is called, |
| * where {@code refcPkg} is the package of {@code refc}. |
| * <li><b>Step 2:</b> |
| * If the retrieved member is not public and |
| * {@code lookc} is not present, then |
| * {@link SecurityManager#checkPermission smgr.checkPermission} |
| * with {@code RuntimePermission("accessDeclaredMembers")} is called. |
| * <li><b>Step 3:</b> |
| * If the retrieved member is not public, |
| * and if {@code lookc} is not present, |
| * and if {@code defc} and {@code refc} are different, |
| * then {@link SecurityManager#checkPackageAccess |
| * smgr.checkPackageAccess(defcPkg)} is called, |
| * where {@code defcPkg} is the package of {@code defc}. |
| * </ul> |
| * Security checks are performed after other access checks have passed. |
| * Therefore, the above rules presuppose a member that is public, |
| * or else that is being accessed from a lookup class that has |
| * rights to access the member. |
| * |
| * <h1><a name="callsens"></a>Caller sensitive methods</h1> |
| * A small number of Java methods have a special property called caller sensitivity. |
| * A <em>caller-sensitive</em> method can behave differently depending on the |
| * identity of its immediate caller. |
| * <p> |
| * If a method handle for a caller-sensitive method is requested, |
| * the general rules for <a href="MethodHandles.Lookup.html#equiv">bytecode behaviors</a> apply, |
| * but they take account of the lookup class in a special way. |
| * The resulting method handle behaves as if it were called |
| * from an instruction contained in the lookup class, |
| * so that the caller-sensitive method detects the lookup class. |
| * (By contrast, the invoker of the method handle is disregarded.) |
| * Thus, in the case of caller-sensitive methods, |
| * different lookup classes may give rise to |
| * differently behaving method handles. |
| * <p> |
| * In cases where the lookup object is |
| * {@link #publicLookup publicLookup()}, |
| * or some other lookup object without |
| * <a href="MethodHandles.Lookup.html#privacc">private access</a>, |
| * the lookup class is disregarded. |
| * In such cases, no caller-sensitive method handle can be created, |
| * access is forbidden, and the lookup fails with an |
| * {@code IllegalAccessException}. |
| * <p style="font-size:smaller;"> |
| * <em>Discussion:</em> |
| * For example, the caller-sensitive method |
| * {@link java.lang.Class#forName(String) Class.forName(x)} |
| * can return varying classes or throw varying exceptions, |
| * depending on the class loader of the class that calls it. |
| * A public lookup of {@code Class.forName} will fail, because |
| * there is no reasonable way to determine its bytecode behavior. |
| * <p style="font-size:smaller;"> |
| * If an application caches method handles for broad sharing, |
| * it should use {@code publicLookup()} to create them. |
| * If there is a lookup of {@code Class.forName}, it will fail, |
| * and the application must take appropriate action in that case. |
| * It may be that a later lookup, perhaps during the invocation of a |
| * bootstrap method, can incorporate the specific identity |
| * of the caller, making the method accessible. |
| * <p style="font-size:smaller;"> |
| * The function {@code MethodHandles.lookup} is caller sensitive |
| * so that there can be a secure foundation for lookups. |
| * Nearly all other methods in the JSR 292 API rely on lookup |
| * objects to check access requests. |
| */ |
| // Android-changed: Change link targets from MethodHandles#[public]Lookup to |
| // #[public]Lookup to work around complaints from javadoc. |
| public static final |
| class Lookup { |
| /** The class on behalf of whom the lookup is being performed. */ |
| /* @NonNull */ private final Class<?> lookupClass; |
| |
| /** The allowed sorts of members which may be looked up (PUBLIC, etc.). */ |
| private final int allowedModes; |
| |
| /** A single-bit mask representing {@code public} access, |
| * which may contribute to the result of {@link #lookupModes lookupModes}. |
| * The value, {@code 0x01}, happens to be the same as the value of the |
| * {@code public} {@linkplain java.lang.reflect.Modifier#PUBLIC modifier bit}. |
| */ |
| public static final int PUBLIC = Modifier.PUBLIC; |
| |
| /** A single-bit mask representing {@code private} access, |
| * which may contribute to the result of {@link #lookupModes lookupModes}. |
| * The value, {@code 0x02}, happens to be the same as the value of the |
| * {@code private} {@linkplain java.lang.reflect.Modifier#PRIVATE modifier bit}. |
| */ |
| public static final int PRIVATE = Modifier.PRIVATE; |
| |
| /** A single-bit mask representing {@code protected} access, |
| * which may contribute to the result of {@link #lookupModes lookupModes}. |
| * The value, {@code 0x04}, happens to be the same as the value of the |
| * {@code protected} {@linkplain java.lang.reflect.Modifier#PROTECTED modifier bit}. |
| */ |
| public static final int PROTECTED = Modifier.PROTECTED; |
| |
| /** A single-bit mask representing {@code package} access (default access), |
| * which may contribute to the result of {@link #lookupModes lookupModes}. |
| * The value is {@code 0x08}, which does not correspond meaningfully to |
| * any particular {@linkplain java.lang.reflect.Modifier modifier bit}. |
| */ |
| public static final int PACKAGE = Modifier.STATIC; |
| |
| private static final int ALL_MODES = (PUBLIC | PRIVATE | PROTECTED | PACKAGE); |
| |
| // Android-note: Android has no notion of a trusted lookup. If required, such lookups |
| // are performed by the runtime. As a result, we always use lookupClass, which will always |
| // be non-null in our implementation. |
| // |
| // private static final int TRUSTED = -1; |
| |
| private static int fixmods(int mods) { |
| mods &= (ALL_MODES - PACKAGE); |
| return (mods != 0) ? mods : PACKAGE; |
| } |
| |
| /** Tells which class is performing the lookup. It is this class against |
| * which checks are performed for visibility and access permissions. |
| * <p> |
| * The class implies a maximum level of access permission, |
| * but the permissions may be additionally limited by the bitmask |
| * {@link #lookupModes lookupModes}, which controls whether non-public members |
| * can be accessed. |
| * @return the lookup class, on behalf of which this lookup object finds members |
| */ |
| public Class<?> lookupClass() { |
| return lookupClass; |
| } |
| |
| /** Tells which access-protection classes of members this lookup object can produce. |
| * The result is a bit-mask of the bits |
| * {@linkplain #PUBLIC PUBLIC (0x01)}, |
| * {@linkplain #PRIVATE PRIVATE (0x02)}, |
| * {@linkplain #PROTECTED PROTECTED (0x04)}, |
| * and {@linkplain #PACKAGE PACKAGE (0x08)}. |
| * <p> |
| * A freshly-created lookup object |
| * on the {@linkplain java.lang.invoke.MethodHandles#lookup() caller's class} |
| * has all possible bits set, since the caller class can access all its own members. |
| * A lookup object on a new lookup class |
| * {@linkplain java.lang.invoke.MethodHandles.Lookup#in created from a previous lookup object} |
| * may have some mode bits set to zero. |
| * The purpose of this is to restrict access via the new lookup object, |
| * so that it can access only names which can be reached by the original |
| * lookup object, and also by the new lookup class. |
| * @return the lookup modes, which limit the kinds of access performed by this lookup object |
| */ |
| public int lookupModes() { |
| return allowedModes & ALL_MODES; |
| } |
| |
| /** Embody the current class (the lookupClass) as a lookup class |
| * for method handle creation. |
| * Must be called by from a method in this package, |
| * which in turn is called by a method not in this package. |
| */ |
| Lookup(Class<?> lookupClass) { |
| this(lookupClass, ALL_MODES); |
| // make sure we haven't accidentally picked up a privileged class: |
| checkUnprivilegedlookupClass(lookupClass, ALL_MODES); |
| } |
| |
| private Lookup(Class<?> lookupClass, int allowedModes) { |
| this.lookupClass = lookupClass; |
| this.allowedModes = allowedModes; |
| } |
| |
| /** |
| * Creates a lookup on the specified new lookup class. |
| * The resulting object will report the specified |
| * class as its own {@link #lookupClass lookupClass}. |
| * <p> |
| * However, the resulting {@code Lookup} object is guaranteed |
| * to have no more access capabilities than the original. |
| * In particular, access capabilities can be lost as follows:<ul> |
| * <li>If the new lookup class differs from the old one, |
| * protected members will not be accessible by virtue of inheritance. |
| * (Protected members may continue to be accessible because of package sharing.) |
| * <li>If the new lookup class is in a different package |
| * than the old one, protected and default (package) members will not be accessible. |
| * <li>If the new lookup class is not within the same package member |
| * as the old one, private members will not be accessible. |
| * <li>If the new lookup class is not accessible to the old lookup class, |
| * then no members, not even public members, will be accessible. |
| * (In all other cases, public members will continue to be accessible.) |
| * </ul> |
| * |
| * @param requestedLookupClass the desired lookup class for the new lookup object |
| * @return a lookup object which reports the desired lookup class |
| * @throws NullPointerException if the argument is null |
| */ |
| public Lookup in(Class<?> requestedLookupClass) { |
| requestedLookupClass.getClass(); // null check |
| // Android-changed: There's no notion of a trusted lookup. |
| // if (allowedModes == TRUSTED) // IMPL_LOOKUP can make any lookup at all |
| // return new Lookup(requestedLookupClass, ALL_MODES); |
| |
| if (requestedLookupClass == this.lookupClass) |
| return this; // keep same capabilities |
| int newModes = (allowedModes & (ALL_MODES & ~PROTECTED)); |
| if ((newModes & PACKAGE) != 0 |
| && !VerifyAccess.isSamePackage(this.lookupClass, requestedLookupClass)) { |
| newModes &= ~(PACKAGE|PRIVATE); |
| } |
| // Allow nestmate lookups to be created without special privilege: |
| if ((newModes & PRIVATE) != 0 |
| && !VerifyAccess.isSamePackageMember(this.lookupClass, requestedLookupClass)) { |
| newModes &= ~PRIVATE; |
| } |
| if ((newModes & PUBLIC) != 0 |
| && !VerifyAccess.isClassAccessible(requestedLookupClass, this.lookupClass, allowedModes)) { |
| // The requested class it not accessible from the lookup class. |
| // No permissions. |
| newModes = 0; |
| } |
| checkUnprivilegedlookupClass(requestedLookupClass, newModes); |
| return new Lookup(requestedLookupClass, newModes); |
| } |
| |
| // Make sure outer class is initialized first. |
| // |
| // Android-changed: Removed unnecessary reference to IMPL_NAMES. |
| // static { IMPL_NAMES.getClass(); } |
| |
| /** Version of lookup which is trusted minimally. |
| * It can only be used to create method handles to |
| * publicly accessible members. |
| */ |
| static final Lookup PUBLIC_LOOKUP = new Lookup(Object.class, PUBLIC); |
| |
| /** Package-private version of lookup which is trusted. */ |
| static final Lookup IMPL_LOOKUP = new Lookup(Object.class, ALL_MODES); |
| |
| private static void checkUnprivilegedlookupClass(Class<?> lookupClass, int allowedModes) { |
| String name = lookupClass.getName(); |
| if (name.startsWith("java.lang.invoke.")) |
| throw newIllegalArgumentException("illegal lookupClass: "+lookupClass); |
| |
| // For caller-sensitive MethodHandles.lookup() |
| // disallow lookup more restricted packages |
| // |
| // Android-changed: The bootstrap classloader isn't null. |
| if (allowedModes == ALL_MODES && |
| lookupClass.getClassLoader() == Object.class.getClassLoader()) { |
| if ((name.startsWith("java.") |
| && !name.startsWith("java.io.ObjectStreamClass") |
| && !name.startsWith("java.util.concurrent.") |
| && !name.equals("java.lang.Daemons$FinalizerWatchdogDaemon") |
| && !name.equals("java.lang.runtime.ObjectMethods") |
| && !name.equals("java.lang.Thread")) || |
| (name.startsWith("sun.") |
| && !name.startsWith("sun.invoke.") |
| && !name.equals("sun.reflect.ReflectionFactory"))) { |
| throw newIllegalArgumentException("illegal lookupClass: " + lookupClass); |
| } |
| } |
| } |
| |
| /** |
| * Displays the name of the class from which lookups are to be made. |
| * (The name is the one reported by {@link java.lang.Class#getName() Class.getName}.) |
| * If there are restrictions on the access permitted to this lookup, |
| * this is indicated by adding a suffix to the class name, consisting |
| * of a slash and a keyword. The keyword represents the strongest |
| * allowed access, and is chosen as follows: |
| * <ul> |
| * <li>If no access is allowed, the suffix is "/noaccess". |
| * <li>If only public access is allowed, the suffix is "/public". |
| * <li>If only public and package access are allowed, the suffix is "/package". |
| * <li>If only public, package, and private access are allowed, the suffix is "/private". |
| * </ul> |
| * If none of the above cases apply, it is the case that full |
| * access (public, package, private, and protected) is allowed. |
| * In this case, no suffix is added. |
| * This is true only of an object obtained originally from |
| * {@link java.lang.invoke.MethodHandles#lookup MethodHandles.lookup}. |
| * Objects created by {@link java.lang.invoke.MethodHandles.Lookup#in Lookup.in} |
| * always have restricted access, and will display a suffix. |
| * <p> |
| * (It may seem strange that protected access should be |
| * stronger than private access. Viewed independently from |
| * package access, protected access is the first to be lost, |
| * because it requires a direct subclass relationship between |
| * caller and callee.) |
| * @see #in |
| */ |
| @Override |
| public String toString() { |
| String cname = lookupClass.getName(); |
| switch (allowedModes) { |
| case 0: // no privileges |
| return cname + "/noaccess"; |
| case PUBLIC: |
| return cname + "/public"; |
| case PUBLIC|PACKAGE: |
| return cname + "/package"; |
| case ALL_MODES & ~PROTECTED: |
| return cname + "/private"; |
| case ALL_MODES: |
| return cname; |
| // Android-changed: No support for TRUSTED callers. |
| // case TRUSTED: |
| // return "/trusted"; // internal only; not exported |
| default: // Should not happen, but it's a bitfield... |
| cname = cname + "/" + Integer.toHexString(allowedModes); |
| assert(false) : cname; |
| return cname; |
| } |
| } |
| |
| /** |
| * Produces a method handle for a static method. |
| * The type of the method handle will be that of the method. |
| * (Since static methods do not take receivers, there is no |
| * additional receiver argument inserted into the method handle type, |
| * as there would be with {@link #findVirtual findVirtual} or {@link #findSpecial findSpecial}.) |
| * The method and all its argument types must be accessible to the lookup object. |
| * <p> |
| * The returned method handle will have |
| * {@linkplain MethodHandle#asVarargsCollector variable arity} if and only if |
| * the method's variable arity modifier bit ({@code 0x0080}) is set. |
| * <p> |
| * If the returned method handle is invoked, the method's class will |
| * be initialized, if it has not already been initialized. |
| * <p><b>Example:</b> |
| * <blockquote><pre>{@code |
| import static java.lang.invoke.MethodHandles.*; |
| import static java.lang.invoke.MethodType.*; |
| ... |
| MethodHandle MH_asList = publicLookup().findStatic(Arrays.class, |
| "asList", methodType(List.class, Object[].class)); |
| assertEquals("[x, y]", MH_asList.invoke("x", "y").toString()); |
| * }</pre></blockquote> |
| * @param refc the class from which the method is accessed |
| * @param name the name of the method |
| * @param type the type of the method |
| * @return the desired method handle |
| * @throws NoSuchMethodException if the method does not exist |
| * @throws IllegalAccessException if access checking fails, |
| * or if the method is not {@code static}, |
| * or if the method's variable arity modifier bit |
| * is set and {@code asVarargsCollector} fails |
| * @exception SecurityException if a security manager is present and it |
| * <a href="MethodHandles.Lookup.html#secmgr">refuses access</a> |
| * @throws NullPointerException if any argument is null |
| */ |
| public |
| MethodHandle findStatic(Class<?> refc, String name, MethodType type) throws NoSuchMethodException, IllegalAccessException { |
| Method method = refc.getDeclaredMethod(name, type.ptypes()); |
| final int modifiers = method.getModifiers(); |
| if (!Modifier.isStatic(modifiers)) { |
| throw new IllegalAccessException("Method" + method + " is not static"); |
| } |
| checkReturnType(method, type); |
| checkAccess(refc, method.getDeclaringClass(), modifiers, method.getName()); |
| return createMethodHandle(method, MethodHandle.INVOKE_STATIC, type); |
| } |
| |
| private MethodHandle findVirtualForMH(String name, MethodType type) { |
| // these names require special lookups because of the implicit MethodType argument |
| if ("invoke".equals(name)) |
| return invoker(type); |
| if ("invokeExact".equals(name)) |
| return exactInvoker(type); |
| return null; |
| } |
| |
| private MethodHandle findVirtualForVH(String name, MethodType type) { |
| VarHandle.AccessMode accessMode; |
| try { |
| accessMode = VarHandle.AccessMode.valueFromMethodName(name); |
| } catch (IllegalArgumentException e) { |
| return null; |
| } |
| return varHandleInvoker(accessMode, type); |
| } |
| |
| private static MethodHandle createMethodHandle(Method method, int handleKind, |
| MethodType methodType) { |
| MethodHandle mh = new MethodHandleImpl(method.getArtMethod(), handleKind, methodType); |
| if (method.isVarArgs()) { |
| return new Transformers.VarargsCollector(mh); |
| } else { |
| return mh; |
| } |
| } |
| |
| /** |
| * Produces a method handle for a virtual method. |
| * The type of the method handle will be that of the method, |
| * with the receiver type (usually {@code refc}) prepended. |
| * The method and all its argument types must be accessible to the lookup object. |
| * <p> |
| * When called, the handle will treat the first argument as a receiver |
| * and dispatch on the receiver's type to determine which method |
| * implementation to enter. |
| * (The dispatching action is identical with that performed by an |
| * {@code invokevirtual} or {@code invokeinterface} instruction.) |
| * <p> |
| * The first argument will be of type {@code refc} if the lookup |
| * class has full privileges to access the member. Otherwise |
| * the member must be {@code protected} and the first argument |
| * will be restricted in type to the lookup class. |
| * <p> |
| * The returned method handle will have |
| * {@linkplain MethodHandle#asVarargsCollector variable arity} if and only if |
| * the method's variable arity modifier bit ({@code 0x0080}) is set. |
| * <p> |
| * Because of the general <a href="MethodHandles.Lookup.html#equiv">equivalence</a> between {@code invokevirtual} |
| * instructions and method handles produced by {@code findVirtual}, |
| * if the class is {@code MethodHandle} and the name string is |
| * {@code invokeExact} or {@code invoke}, the resulting |
| * method handle is equivalent to one produced by |
| * {@link java.lang.invoke.MethodHandles#exactInvoker MethodHandles.exactInvoker} or |
| * {@link java.lang.invoke.MethodHandles#invoker MethodHandles.invoker} |
| * with the same {@code type} argument. |
| * |
| * <b>Example:</b> |
| * <blockquote><pre>{@code |
| import static java.lang.invoke.MethodHandles.*; |
| import static java.lang.invoke.MethodType.*; |
| ... |
| MethodHandle MH_concat = publicLookup().findVirtual(String.class, |
| "concat", methodType(String.class, String.class)); |
| MethodHandle MH_hashCode = publicLookup().findVirtual(Object.class, |
| "hashCode", methodType(int.class)); |
| MethodHandle MH_hashCode_String = publicLookup().findVirtual(String.class, |
| "hashCode", methodType(int.class)); |
| assertEquals("xy", (String) MH_concat.invokeExact("x", "y")); |
| assertEquals("xy".hashCode(), (int) MH_hashCode.invokeExact((Object)"xy")); |
| assertEquals("xy".hashCode(), (int) MH_hashCode_String.invokeExact("xy")); |
| // interface method: |
| MethodHandle MH_subSequence = publicLookup().findVirtual(CharSequence.class, |
| "subSequence", methodType(CharSequence.class, int.class, int.class)); |
| assertEquals("def", MH_subSequence.invoke("abcdefghi", 3, 6).toString()); |
| // constructor "internal method" must be accessed differently: |
| MethodType MT_newString = methodType(void.class); //()V for new String() |
| try { assertEquals("impossible", lookup() |
| .findVirtual(String.class, "<init>", MT_newString)); |
| } catch (NoSuchMethodException ex) { } // OK |
| MethodHandle MH_newString = publicLookup() |
| .findConstructor(String.class, MT_newString); |
| assertEquals("", (String) MH_newString.invokeExact()); |
| * }</pre></blockquote> |
| * |
| * @param refc the class or interface from which the method is accessed |
| * @param name the name of the method |
| * @param type the type of the method, with the receiver argument omitted |
| * @return the desired method handle |
| * @throws NoSuchMethodException if the method does not exist |
| * @throws IllegalAccessException if access checking fails, |
| * or if the method is {@code static} |
| * or if the method's variable arity modifier bit |
| * is set and {@code asVarargsCollector} fails |
| * @exception SecurityException if a security manager is present and it |
| * <a href="MethodHandles.Lookup.html#secmgr">refuses access</a> |
| * @throws NullPointerException if any argument is null |
| */ |
| public MethodHandle findVirtual(Class<?> refc, String name, MethodType type) throws NoSuchMethodException, IllegalAccessException { |
| // Special case : when we're looking up a virtual method on the MethodHandles class |
| // itself, we can return one of our specialized invokers. |
| if (refc == MethodHandle.class) { |
| MethodHandle mh = findVirtualForMH(name, type); |
| if (mh != null) { |
| return mh; |
| } |
| } else if (refc == VarHandle.class) { |
| // Returns an non-exact invoker. |
| MethodHandle mh = findVirtualForVH(name, type); |
| if (mh != null) { |
| return mh; |
| } |
| } |
| |
| Method method = refc.getInstanceMethod(name, type.ptypes()); |
| if (method == null) { |
| // This is pretty ugly and a consequence of the MethodHandles API. We have to throw |
| // an IAE and not an NSME if the method exists but is static (even though the RI's |
| // IAE has a message that says "no such method"). We confine the ugliness and |
| // slowness to the failure case, and allow getInstanceMethod to remain fairly |
| // general. |
| try { |
| Method m = refc.getDeclaredMethod(name, type.ptypes()); |
| if (Modifier.isStatic(m.getModifiers())) { |
| throw new IllegalAccessException("Method" + m + " is static"); |
| } |
| } catch (NoSuchMethodException ignored) { |
| } |
| |
| throw new NoSuchMethodException(name + " " + Arrays.toString(type.ptypes())); |
| } |
| checkReturnType(method, type); |
| |
| // We have a valid method, perform access checks. |
| checkAccess(refc, method.getDeclaringClass(), method.getModifiers(), method.getName()); |
| |
| // Insert the leading reference parameter. |
| MethodType handleType = type.insertParameterTypes(0, refc); |
| return createMethodHandle(method, MethodHandle.INVOKE_VIRTUAL, handleType); |
| } |
| |
| /** |
| * Produces a method handle which creates an object and initializes it, using |
| * the constructor of the specified type. |
| * The parameter types of the method handle will be those of the constructor, |
| * while the return type will be a reference to the constructor's class. |
| * The constructor and all its argument types must be accessible to the lookup object. |
| * <p> |
| * The requested type must have a return type of {@code void}. |
| * (This is consistent with the JVM's treatment of constructor type descriptors.) |
| * <p> |
| * The returned method handle will have |
| * {@linkplain MethodHandle#asVarargsCollector variable arity} if and only if |
| * the constructor's variable arity modifier bit ({@code 0x0080}) is set. |
| * <p> |
| * If the returned method handle is invoked, the constructor's class will |
| * be initialized, if it has not already been initialized. |
| * <p><b>Example:</b> |
| * <blockquote><pre>{@code |
| import static java.lang.invoke.MethodHandles.*; |
| import static java.lang.invoke.MethodType.*; |
| ... |
| MethodHandle MH_newArrayList = publicLookup().findConstructor( |
| ArrayList.class, methodType(void.class, Collection.class)); |
| Collection orig = Arrays.asList("x", "y"); |
| Collection copy = (ArrayList) MH_newArrayList.invokeExact(orig); |
| assert(orig != copy); |
| assertEquals(orig, copy); |
| // a variable-arity constructor: |
| MethodHandle MH_newProcessBuilder = publicLookup().findConstructor( |
| ProcessBuilder.class, methodType(void.class, String[].class)); |
| ProcessBuilder pb = (ProcessBuilder) |
| MH_newProcessBuilder.invoke("x", "y", "z"); |
| assertEquals("[x, y, z]", pb.command().toString()); |
| * }</pre></blockquote> |
| * @param refc the class or interface from which the method is accessed |
| * @param type the type of the method, with the receiver argument omitted, and a void return type |
| * @return the desired method handle |
| * @throws NoSuchMethodException if the constructor does not exist |
| * @throws IllegalAccessException if access checking fails |
| * or if the method's variable arity modifier bit |
| * is set and {@code asVarargsCollector} fails |
| * @exception SecurityException if a security manager is present and it |
| * <a href="MethodHandles.Lookup.html#secmgr">refuses access</a> |
| * @throws NullPointerException if any argument is null |
| */ |
| public MethodHandle findConstructor(Class<?> refc, MethodType type) throws NoSuchMethodException, IllegalAccessException { |
| if (refc.isArray()) { |
| throw new NoSuchMethodException("no constructor for array class: " + refc.getName()); |
| } |
| // The queried |type| is (PT1,PT2,..)V |
| Constructor constructor = refc.getDeclaredConstructor(type.ptypes()); |
| if (constructor == null) { |
| throw new NoSuchMethodException( |
| "No constructor for " + constructor.getDeclaringClass() + " matching " + type); |
| } |
| checkAccess(refc, constructor.getDeclaringClass(), constructor.getModifiers(), |
| constructor.getName()); |
| |
| return createMethodHandleForConstructor(constructor); |
| } |
| |
| // BEGIN Android-added: Add findClass(String) from OpenJDK 17. http://b/270028670 |
| // TODO: Unhide this method. |
| /** |
| * Looks up a class by name from the lookup context defined by this {@code Lookup} object, |
| * <a href="MethodHandles.Lookup.html#equiv">as if resolved</a> by an {@code ldc} instruction. |
| * Such a resolution, as specified in JVMS 5.4.3.1 section, attempts to locate and load the class, |
| * and then determines whether the class is accessible to this lookup object. |
| * <p> |
| * The lookup context here is determined by the {@linkplain #lookupClass() lookup class}, |
| * its class loader, and the {@linkplain #lookupModes() lookup modes}. |
| * |
| * @param targetName the fully qualified name of the class to be looked up. |
| * @return the requested class. |
| * @throws SecurityException if a security manager is present and it |
| * <a href="MethodHandles.Lookup.html#secmgr">refuses access</a> |
| * @throws LinkageError if the linkage fails |
| * @throws ClassNotFoundException if the class cannot be loaded by the lookup class' loader. |
| * @throws IllegalAccessException if the class is not accessible, using the allowed access |
| * modes. |
| * @throws NullPointerException if {@code targetName} is null |
| * @since 9 |
| * @jvms 5.4.3.1 Class and Interface Resolution |
| * @hide |
| */ |
| public Class<?> findClass(String targetName) throws ClassNotFoundException, IllegalAccessException { |
| Class<?> targetClass = Class.forName(targetName, false, lookupClass.getClassLoader()); |
| return accessClass(targetClass); |
| } |
| // END Android-added: Add findClass(String) from OpenJDK 17. http://b/270028670 |
| |
| private MethodHandle createMethodHandleForConstructor(Constructor constructor) { |
| Class<?> refc = constructor.getDeclaringClass(); |
| MethodType constructorType = |
| MethodType.methodType(refc, constructor.getParameterTypes()); |
| MethodHandle mh; |
| if (refc == String.class) { |
| // String constructors have optimized StringFactory methods |
| // that matches returned type. These factory methods combine the |
| // memory allocation and initialization calls for String objects. |
| mh = new MethodHandleImpl(constructor.getArtMethod(), MethodHandle.INVOKE_DIRECT, |
| constructorType); |
| } else { |
| // Constructors for all other classes use a Construct transformer to perform |
| // their memory allocation and call to <init>. |
| MethodType initType = initMethodType(constructorType); |
| MethodHandle initHandle = new MethodHandleImpl( |
| constructor.getArtMethod(), MethodHandle.INVOKE_DIRECT, initType); |
| mh = new Transformers.Construct(initHandle, constructorType); |
| } |
| |
| if (constructor.isVarArgs()) { |
| mh = new Transformers.VarargsCollector(mh); |
| } |
| return mh; |
| } |
| |
| private static MethodType initMethodType(MethodType constructorType) { |
| // Returns a MethodType appropriate for class <init> |
| // methods. Constructor MethodTypes have the form |
| // (PT1,PT2,...)C and class <init> MethodTypes have the |
| // form (C,PT1,PT2,...)V. |
| assert constructorType.rtype() != void.class; |
| |
| // Insert constructorType C as the first parameter type in |
| // the MethodType for <init>. |
| Class<?> [] initPtypes = new Class<?> [constructorType.ptypes().length + 1]; |
| initPtypes[0] = constructorType.rtype(); |
| System.arraycopy(constructorType.ptypes(), 0, initPtypes, 1, |
| constructorType.ptypes().length); |
| |
| // Set the return type for the <init> MethodType to be void. |
| return MethodType.methodType(void.class, initPtypes); |
| } |
| |
| // BEGIN Android-added: Add accessClass(Class) from OpenJDK 17. http://b/270028670 |
| /* |
| * Returns IllegalAccessException due to access violation to the given targetClass. |
| * |
| * This method is called by {@link Lookup#accessClass} and {@link Lookup#ensureInitialized} |
| * which verifies access to a class rather a member. |
| */ |
| private IllegalAccessException makeAccessException(Class<?> targetClass) { |
| String message = "access violation: "+ targetClass; |
| if (this == MethodHandles.publicLookup()) { |
| message += ", from public Lookup"; |
| } else { |
| // Android-changed: Remove unsupported module name. |
| // Module m = lookupClass().getModule(); |
| // message += ", from " + lookupClass() + " (" + m + ")"; |
| message += ", from " + lookupClass(); |
| // Android-removed: Remove prevLookupClass until supported by Lookup in OpenJDK 17. |
| // if (prevLookupClass != null) { |
| // message += ", previous lookup " + |
| // prevLookupClass.getName() + " (" + prevLookupClass.getModule() + ")"; |
| // } |
| } |
| return new IllegalAccessException(message); |
| } |
| |
| // TODO: Unhide this method. |
| /** |
| * Determines if a class can be accessed from the lookup context defined by |
| * this {@code Lookup} object. The static initializer of the class is not run. |
| * If {@code targetClass} is an array class, {@code targetClass} is accessible |
| * if the element type of the array class is accessible. Otherwise, |
| * {@code targetClass} is determined as accessible as follows. |
| * |
| * <p> |
| * If {@code targetClass} is in the same module as the lookup class, |
| * the lookup class is {@code LC} in module {@code M1} and |
| * the previous lookup class is in module {@code M0} or |
| * {@code null} if not present, |
| * {@code targetClass} is accessible if and only if one of the following is true: |
| * <ul> |
| * <li>If this lookup has {@link #PRIVATE} access, {@code targetClass} is |
| * {@code LC} or other class in the same nest of {@code LC}.</li> |
| * <li>If this lookup has {@link #PACKAGE} access, {@code targetClass} is |
| * in the same runtime package of {@code LC}.</li> |
| * <li>If this lookup has {@link #MODULE} access, {@code targetClass} is |
| * a public type in {@code M1}.</li> |
| * <li>If this lookup has {@link #PUBLIC} access, {@code targetClass} is |
| * a public type in a package exported by {@code M1} to at least {@code M0} |
| * if the previous lookup class is present; otherwise, {@code targetClass} |
| * is a public type in a package exported by {@code M1} unconditionally.</li> |
| * </ul> |
| * |
| * <p> |
| * Otherwise, if this lookup has {@link #UNCONDITIONAL} access, this lookup |
| * can access public types in all modules when the type is in a package |
| * that is exported unconditionally. |
| * <p> |
| * Otherwise, {@code targetClass} is in a different module from {@code lookupClass}, |
| * and if this lookup does not have {@code PUBLIC} access, {@code lookupClass} |
| * is inaccessible. |
| * <p> |
| * Otherwise, if this lookup has no {@linkplain #previousLookupClass() previous lookup class}, |
| * {@code M1} is the module containing {@code lookupClass} and |
| * {@code M2} is the module containing {@code targetClass}, |
| * then {@code targetClass} is accessible if and only if |
| * <ul> |
| * <li>{@code M1} reads {@code M2}, and |
| * <li>{@code targetClass} is public and in a package exported by |
| * {@code M2} at least to {@code M1}. |
| * </ul> |
| * <p> |
| * Otherwise, if this lookup has a {@linkplain #previousLookupClass() previous lookup class}, |
| * {@code M1} and {@code M2} are as before, and {@code M0} is the module |
| * containing the previous lookup class, then {@code targetClass} is accessible |
| * if and only if one of the following is true: |
| * <ul> |
| * <li>{@code targetClass} is in {@code M0} and {@code M1} |
| * {@linkplain Module#reads reads} {@code M0} and the type is |
| * in a package that is exported to at least {@code M1}. |
| * <li>{@code targetClass} is in {@code M1} and {@code M0} |
| * {@linkplain Module#reads reads} {@code M1} and the type is |
| * in a package that is exported to at least {@code M0}. |
| * <li>{@code targetClass} is in a third module {@code M2} and both {@code M0} |
| * and {@code M1} reads {@code M2} and the type is in a package |
| * that is exported to at least both {@code M0} and {@code M2}. |
| * </ul> |
| * <p> |
| * Otherwise, {@code targetClass} is not accessible. |
| * |
| * @param targetClass the class to be access-checked |
| * @return the class that has been access-checked |
| * @throws IllegalAccessException if the class is not accessible from the lookup class |
| * and previous lookup class, if present, using the allowed access modes. |
| * @throws SecurityException if a security manager is present and it |
| * <a href="MethodHandles.Lookup.html#secmgr">refuses access</a> |
| * @throws NullPointerException if {@code targetClass} is {@code null} |
| * @since 9 |
| * @see <a href="#cross-module-lookup">Cross-module lookups</a> |
| * @hide |
| */ |
| public Class<?> accessClass(Class<?> targetClass) throws IllegalAccessException { |
| if (!isClassAccessible(targetClass)) { |
| throw makeAccessException(targetClass); |
| } |
| // Android-removed: SecurityManager is unnecessary on Android. |
| // checkSecurityManager(targetClass); |
| return targetClass; |
| } |
| |
| boolean isClassAccessible(Class<?> refc) { |
| Objects.requireNonNull(refc); |
| Class<?> caller = lookupClassOrNull(); |
| Class<?> type = refc; |
| while (type.isArray()) { |
| type = type.getComponentType(); |
| } |
| // Android-removed: Remove prevLookupClass until supported by Lookup in OpenJDK 17. |
| // return caller == null || VerifyAccess.isClassAccessible(type, caller, prevLookupClass, allowedModes); |
| return caller == null || VerifyAccess.isClassAccessible(type, caller, allowedModes); |
| } |
| |
| // This is just for calling out to MethodHandleImpl. |
| private Class<?> lookupClassOrNull() { |
| // Android-changed: Android always returns lookupClass and has no concept of TRUSTED. |
| // return (allowedModes == TRUSTED) ? null : lookupClass; |
| return lookupClass; |
| } |
| // END Android-added: Add accessClass(Class) from OpenJDK 17. http://b/270028670 |
| |
| /** |
| * Produces an early-bound method handle for a virtual method. |
| * It will bypass checks for overriding methods on the receiver, |
| * <a href="MethodHandles.Lookup.html#equiv">as if called</a> from an {@code invokespecial} |
| * instruction from within the explicitly specified {@code specialCaller}. |
| * The type of the method handle will be that of the method, |
| * with a suitably restricted receiver type prepended. |
| * (The receiver type will be {@code specialCaller} or a subtype.) |
| * The method and all its argument types must be accessible |
| * to the lookup object. |
| * <p> |
| * Before method resolution, |
| * if the explicitly specified caller class is not identical with the |
| * lookup class, or if this lookup object does not have |
| * <a href="MethodHandles.Lookup.html#privacc">private access</a> |
| * privileges, the access fails. |
| * <p> |
| * The returned method handle will have |
| * {@linkplain MethodHandle#asVarargsCollector variable arity} if and only if |
| * the method's variable arity modifier bit ({@code 0x0080}) is set. |
| * <p style="font-size:smaller;"> |
| * <em>(Note: JVM internal methods named {@code "<init>"} are not visible to this API, |
| * even though the {@code invokespecial} instruction can refer to them |
| * in special circumstances. Use {@link #findConstructor findConstructor} |
| * to access instance initialization methods in a safe manner.)</em> |
| * <p><b>Example:</b> |
| * <blockquote><pre>{@code |
| import static java.lang.invoke.MethodHandles.*; |
| import static java.lang.invoke.MethodType.*; |
| ... |
| static class Listie extends ArrayList { |
| public String toString() { return "[wee Listie]"; } |
| static Lookup lookup() { return MethodHandles.lookup(); } |
| } |
| ... |
| // no access to constructor via invokeSpecial: |
| MethodHandle MH_newListie = Listie.lookup() |
| .findConstructor(Listie.class, methodType(void.class)); |
| Listie l = (Listie) MH_newListie.invokeExact(); |
| try { assertEquals("impossible", Listie.lookup().findSpecial( |
| Listie.class, "<init>", methodType(void.class), Listie.class)); |
| } catch (NoSuchMethodException ex) { } // OK |
| // access to super and self methods via invokeSpecial: |
| MethodHandle MH_super = Listie.lookup().findSpecial( |
| ArrayList.class, "toString" , methodType(String.class), Listie.class); |
| MethodHandle MH_this = Listie.lookup().findSpecial( |
| Listie.class, "toString" , methodType(String.class), Listie.class); |
| MethodHandle MH_duper = Listie.lookup().findSpecial( |
| Object.class, "toString" , methodType(String.class), Listie.class); |
| assertEquals("[]", (String) MH_super.invokeExact(l)); |
| assertEquals(""+l, (String) MH_this.invokeExact(l)); |
| assertEquals("[]", (String) MH_duper.invokeExact(l)); // ArrayList method |
| try { assertEquals("inaccessible", Listie.lookup().findSpecial( |
| String.class, "toString", methodType(String.class), Listie.class)); |
| } catch (IllegalAccessException ex) { } // OK |
| Listie subl = new Listie() { public String toString() { return "[subclass]"; } }; |
| assertEquals(""+l, (String) MH_this.invokeExact(subl)); // Listie method |
| * }</pre></blockquote> |
| * |
| * @param refc the class or interface from which the method is accessed |
| * @param name the name of the method (which must not be "<init>") |
| * @param type the type of the method, with the receiver argument omitted |
| * @param specialCaller the proposed calling class to perform the {@code invokespecial} |
| * @return the desired method handle |
| * @throws NoSuchMethodException if the method does not exist |
| * @throws IllegalAccessException if access checking fails |
| * or if the method's variable arity modifier bit |
| * is set and {@code asVarargsCollector} fails |
| * @exception SecurityException if a security manager is present and it |
| * <a href="MethodHandles.Lookup.html#secmgr">refuses access</a> |
| * @throws NullPointerException if any argument is null |
| */ |
| public MethodHandle findSpecial(Class<?> refc, String name, MethodType type, |
| Class<?> specialCaller) throws NoSuchMethodException, IllegalAccessException { |
| if (specialCaller == null) { |
| throw new NullPointerException("specialCaller == null"); |
| } |
| |
| if (type == null) { |
| throw new NullPointerException("type == null"); |
| } |
| |
| if (name == null) { |
| throw new NullPointerException("name == null"); |
| } |
| |
| if (refc == null) { |
| throw new NullPointerException("ref == null"); |
| } |
| |
| // Make sure that the special caller is identical to the lookup class or that we have |
| // private access. |
| // Android-changed: Also allow access to any interface methods. |
| checkSpecialCaller(specialCaller, refc); |
| |
| // Even though constructors are invoked using a "special" invoke, handles to them can't |
| // be created using findSpecial. Callers must use findConstructor instead. Similarly, |
| // there is no path for calling static class initializers. |
| if (name.startsWith("<")) { |
| throw new NoSuchMethodException(name + " is not a valid method name."); |
| } |
| |
| Method method = refc.getDeclaredMethod(name, type.ptypes()); |
| checkReturnType(method, type); |
| return findSpecial(method, type, refc, specialCaller); |
| } |
| |
| private MethodHandle findSpecial(Method method, MethodType type, |
| Class<?> refc, Class<?> specialCaller) |
| throws IllegalAccessException { |
| if (Modifier.isStatic(method.getModifiers())) { |
| throw new IllegalAccessException("expected a non-static method:" + method); |
| } |
| |
| if (Modifier.isPrivate(method.getModifiers())) { |
| // Since this is a private method, we'll need to also make sure that the |
| // lookup class is the same as the refering class. We've already checked that |
| // the specialCaller is the same as the special lookup class, both of these must |
| // be the same as the declaring class(*) in order to access the private method. |
| // |
| // (*) Well, this isn't true for nested classes but OpenJDK doesn't support those |
| // either. |
| if (refc != lookupClass()) { |
| throw new IllegalAccessException("no private access for invokespecial : " |
| + refc + ", from" + this); |
| } |
| |
| // This is a private method, so there's nothing special to do. |
| MethodType handleType = type.insertParameterTypes(0, refc); |
| return createMethodHandle(method, MethodHandle.INVOKE_DIRECT, handleType); |
| } |
| |
| // This is a public, protected or package-private method, which means we're expecting |
| // invoke-super semantics. We'll have to restrict the receiver type appropriately on the |
| // handle once we check that there really is a "super" relationship between them. |
| if (!method.getDeclaringClass().isAssignableFrom(specialCaller)) { |
| throw new IllegalAccessException(refc + "is not assignable from " + specialCaller); |
| } |
| |
| // Note that we restrict the receiver to "specialCaller" instances. |
| MethodType handleType = type.insertParameterTypes(0, specialCaller); |
| return createMethodHandle(method, MethodHandle.INVOKE_SUPER, handleType); |
| } |
| |
| /** |
| * Produces a method handle giving read access to a non-static field. |
| * The type of the method handle will have a return type of the field's |
| * value type. |
| * The method handle's single argument will be the instance containing |
| * the field. |
| * Access checking is performed immediately on behalf of the lookup class. |
| * @param refc the class or interface from which the method is accessed |
| * @param name the field's name |
| * @param type the field's type |
| * @return a method handle which can load values from the field |
| * @throws NoSuchFieldException if the field does not exist |
| * @throws IllegalAccessException if access checking fails, or if the field is {@code static} |
| * @exception SecurityException if a security manager is present and it |
| * <a href="MethodHandles.Lookup.html#secmgr">refuses access</a> |
| * @throws NullPointerException if any argument is null |
| */ |
| public MethodHandle findGetter(Class<?> refc, String name, Class<?> type) throws NoSuchFieldException, IllegalAccessException { |
| return findAccessor(refc, name, type, MethodHandle.IGET); |
| } |
| |
| private MethodHandle findAccessor(Class<?> refc, String name, Class<?> type, int kind) |
| throws NoSuchFieldException, IllegalAccessException { |
| final Field field = findFieldOfType(refc, name, type); |
| return findAccessor(field, refc, type, kind, true /* performAccessChecks */); |
| } |
| |
| private MethodHandle findAccessor(Field field, Class<?> refc, Class<?> type, int kind, |
| boolean performAccessChecks) |
| throws IllegalAccessException { |
| final boolean isSetterKind = kind == MethodHandle.IPUT || kind == MethodHandle.SPUT; |
| final boolean isStaticKind = kind == MethodHandle.SGET || kind == MethodHandle.SPUT; |
| commonFieldChecks(field, refc, type, isStaticKind, performAccessChecks); |
| if (performAccessChecks) { |
| final int modifiers = field.getModifiers(); |
| if (isSetterKind && Modifier.isFinal(modifiers)) { |
| throw new IllegalAccessException("Field " + field + " is final"); |
| } |
| } |
| |
| final MethodType methodType; |
| switch (kind) { |
| case MethodHandle.SGET: |
| methodType = MethodType.methodType(type); |
| break; |
| case MethodHandle.SPUT: |
| methodType = MethodType.methodType(void.class, type); |
| break; |
| case MethodHandle.IGET: |
| methodType = MethodType.methodType(type, refc); |
| break; |
| case MethodHandle.IPUT: |
| methodType = MethodType.methodType(void.class, refc, type); |
| break; |
| default: |
| throw new IllegalArgumentException("Invalid kind " + kind); |
| } |
| return new MethodHandleImpl(field.getArtField(), kind, methodType); |
| } |
| |
| /** |
| * Produces a method handle giving write access to a non-static field. |
| * The type of the method handle will have a void return type. |
| * The method handle will take two arguments, the instance containing |
| * the field, and the value to be stored. |
| * The second argument will be of the field's value type. |
| * Access checking is performed immediately on behalf of the lookup class. |
| * @param refc the class or interface from which the method is accessed |
| * @param name the field's name |
| * @param type the field's type |
| * @return a method handle which can store values into the field |
| * @throws NoSuchFieldException if the field does not exist |
| * @throws IllegalAccessException if access checking fails, or if the field is {@code static} |
| * @exception SecurityException if a security manager is present and it |
| * <a href="MethodHandles.Lookup.html#secmgr">refuses access</a> |
| * @throws NullPointerException if any argument is null |
| */ |
| public MethodHandle findSetter(Class<?> refc, String name, Class<?> type) throws NoSuchFieldException, IllegalAccessException { |
| return findAccessor(refc, name, type, MethodHandle.IPUT); |
| } |
| |
| // BEGIN Android-changed: OpenJDK 9+181 VarHandle API factory method. |
| /** |
| * Produces a VarHandle giving access to a non-static field {@code name} |
| * of type {@code type} declared in a class of type {@code recv}. |
| * The VarHandle's variable type is {@code type} and it has one |
| * coordinate type, {@code recv}. |
| * <p> |
| * Access checking is performed immediately on behalf of the lookup |
| * class. |
| * <p> |
| * Certain access modes of the returned VarHandle are unsupported under |
| * the following conditions: |
| * <ul> |
| * <li>if the field is declared {@code final}, then the write, atomic |
| * update, numeric atomic update, and bitwise atomic update access |
| * modes are unsupported. |
| * <li>if the field type is anything other than {@code byte}, |
| * {@code short}, {@code char}, {@code int}, {@code long}, |
| * {@code float}, or {@code double} then numeric atomic update |
| * access modes are unsupported. |
| * <li>if the field type is anything other than {@code boolean}, |
| * {@code byte}, {@code short}, {@code char}, {@code int} or |
| * {@code long} then bitwise atomic update access modes are |
| * unsupported. |
| * </ul> |
| * <p> |
| * If the field is declared {@code volatile} then the returned VarHandle |
| * will override access to the field (effectively ignore the |
| * {@code volatile} declaration) in accordance to its specified |
| * access modes. |
| * <p> |
| * If the field type is {@code float} or {@code double} then numeric |
| * and atomic update access modes compare values using their bitwise |
| * representation (see {@link Float#floatToRawIntBits} and |
| * {@link Double#doubleToRawLongBits}, respectively). |
| * @apiNote |
| * Bitwise comparison of {@code float} values or {@code double} values, |
| * as performed by the numeric and atomic update access modes, differ |
| * from the primitive {@code ==} operator and the {@link Float#equals} |
| * and {@link Double#equals} methods, specifically with respect to |
| * comparing NaN values or comparing {@code -0.0} with {@code +0.0}. |
| * Care should be taken when performing a compare and set or a compare |
| * and exchange operation with such values since the operation may |
| * unexpectedly fail. |
| * There are many possible NaN values that are considered to be |
| * {@code NaN} in Java, although no IEEE 754 floating-point operation |
| * provided by Java can distinguish between them. Operation failure can |
| * occur if the expected or witness value is a NaN value and it is |
| * transformed (perhaps in a platform specific manner) into another NaN |
| * value, and thus has a different bitwise representation (see |
| * {@link Float#intBitsToFloat} or {@link Double#longBitsToDouble} for more |
| * details). |
| * The values {@code -0.0} and {@code +0.0} have different bitwise |
| * representations but are considered equal when using the primitive |
| * {@code ==} operator. Operation failure can occur if, for example, a |
| * numeric algorithm computes an expected value to be say {@code -0.0} |
| * and previously computed the witness value to be say {@code +0.0}. |
| * @param recv the receiver class, of type {@code R}, that declares the |
| * non-static field |
| * @param name the field's name |
| * @param type the field's type, of type {@code T} |
| * @return a VarHandle giving access to non-static fields. |
| * @throws NoSuchFieldException if the field does not exist |
| * @throws IllegalAccessException if access checking fails, or if the field is {@code static} |
| * @exception SecurityException if a security manager is present and it |
| * <a href="MethodHandles.Lookup.html#secmgr">refuses access</a> |
| * @throws NullPointerException if any argument is null |
| * @since 9 |
| */ |
| public VarHandle findVarHandle(Class<?> recv, String name, Class<?> type) throws NoSuchFieldException, IllegalAccessException { |
| final Field field = findFieldOfType(recv, name, type); |
| final boolean isStatic = false; |
| final boolean performAccessChecks = true; |
| commonFieldChecks(field, recv, type, isStatic, performAccessChecks); |
| return FieldVarHandle.create(field); |
| } |
| // END Android-changed: OpenJDK 9+181 VarHandle API factory method. |
| |
| // BEGIN Android-added: Common field resolution and access check methods. |
| private Field findFieldOfType(final Class<?> refc, String name, Class<?> type) |
| throws NoSuchFieldException { |
| Field field = null; |
| |
| // Search refc and super classes for the field. |
| for (Class<?> cls = refc; cls != null; cls = cls.getSuperclass()) { |
| try { |
| field = cls.getDeclaredField(name); |
| break; |
| } catch (NoSuchFieldException e) { |
| } |
| } |
| |
| if (field == null) { |
| // Force failure citing refc. |
| field = refc.getDeclaredField(name); |
| } |
| |
| final Class<?> fieldType = field.getType(); |
| if (fieldType != type) { |
| throw new NoSuchFieldException(name); |
| } |
| return field; |
| } |
| |
| private void commonFieldChecks(Field field, Class<?> refc, Class<?> type, |
| boolean isStatic, boolean performAccessChecks) |
| throws IllegalAccessException { |
| final int modifiers = field.getModifiers(); |
| if (performAccessChecks) { |
| checkAccess(refc, field.getDeclaringClass(), modifiers, field.getName()); |
| } |
| if (Modifier.isStatic(modifiers) != isStatic) { |
| String reason = "Field " + field + " is " + |
| (isStatic ? "not " : "") + "static"; |
| throw new IllegalAccessException(reason); |
| } |
| } |
| // END Android-added: Common field resolution and access check methods. |
| |
| /** |
| * Produces a method handle giving read access to a static field. |
| * The type of the method handle will have a return type of the field's |
| * value type. |
| * The method handle will take no arguments. |
| * Access checking is performed immediately on behalf of the lookup class. |
| * <p> |
| * If the returned method handle is invoked, the field's class will |
| * be initialized, if it has not already been initialized. |
| * @param refc the class or interface from which the method is accessed |
| * @param name the field's name |
| * @param type the field's type |
| * @return a method handle which can load values from the field |
| * @throws NoSuchFieldException if the field does not exist |
| * @throws IllegalAccessException if access checking fails, or if the field is not {@code static} |
| * @exception SecurityException if a security manager is present and it |
| * <a href="MethodHandles.Lookup.html#secmgr">refuses access</a> |
| * @throws NullPointerException if any argument is null |
| */ |
| public MethodHandle findStaticGetter(Class<?> refc, String name, Class<?> type) throws NoSuchFieldException, IllegalAccessException { |
| return findAccessor(refc, name, type, MethodHandle.SGET); |
| } |
| |
| /** |
| * Produces a method handle giving write access to a static field. |
| * The type of the method handle will have a void return type. |
| * The method handle will take a single |
| * argument, of the field's value type, the value to be stored. |
| * Access checking is performed immediately on behalf of the lookup class. |
| * <p> |
| * If the returned method handle is invoked, the field's class will |
| * be initialized, if it has not already been initialized. |
| * @param refc the class or interface from which the method is accessed |
| * @param name the field's name |
| * @param type the field's type |
| * @return a method handle which can store values into the field |
| * @throws NoSuchFieldException if the field does not exist |
| * @throws IllegalAccessException if access checking fails, or if the field is not {@code static} |
| * @exception SecurityException if a security manager is present and it |
| * <a href="MethodHandles.Lookup.html#secmgr">refuses access</a> |
| * @throws NullPointerException if any argument is null |
| */ |
| public MethodHandle findStaticSetter(Class<?> refc, String name, Class<?> type) throws NoSuchFieldException, IllegalAccessException { |
| return findAccessor(refc, name, type, MethodHandle.SPUT); |
| } |
| |
| // BEGIN Android-changed: OpenJDK 9+181 VarHandle API factory method. |
| /** |
| * Produces a VarHandle giving access to a static field {@code name} of |
| * type {@code type} declared in a class of type {@code decl}. |
| * The VarHandle's variable type is {@code type} and it has no |
| * coordinate types. |
| * <p> |
| * Access checking is performed immediately on behalf of the lookup |
| * class. |
| * <p> |
| * If the returned VarHandle is operated on, the declaring class will be |
| * initialized, if it has not already been initialized. |
| * <p> |
| * Certain access modes of the returned VarHandle are unsupported under |
| * the following conditions: |
| * <ul> |
| * <li>if the field is declared {@code final}, then the write, atomic |
| * update, numeric atomic update, and bitwise atomic update access |
| * modes are unsupported. |
| * <li>if the field type is anything other than {@code byte}, |
| * {@code short}, {@code char}, {@code int}, {@code long}, |
| * {@code float}, or {@code double}, then numeric atomic update |
| * access modes are unsupported. |
| * <li>if the field type is anything other than {@code boolean}, |
| * {@code byte}, {@code short}, {@code char}, {@code int} or |
| * {@code long} then bitwise atomic update access modes are |
| * unsupported. |
| * </ul> |
| * <p> |
| * If the field is declared {@code volatile} then the returned VarHandle |
| * will override access to the field (effectively ignore the |
| * {@code volatile} declaration) in accordance to its specified |
| * access modes. |
| * <p> |
| * If the field type is {@code float} or {@code double} then numeric |
| * and atomic update access modes compare values using their bitwise |
| * representation (see {@link Float#floatToRawIntBits} and |
| * {@link Double#doubleToRawLongBits}, respectively). |
| * @apiNote |
| * Bitwise comparison of {@code float} values or {@code double} values, |
| * as performed by the numeric and atomic update access modes, differ |
| * from the primitive {@code ==} operator and the {@link Float#equals} |
| * and {@link Double#equals} methods, specifically with respect to |
| * comparing NaN values or comparing {@code -0.0} with {@code +0.0}. |
| * Care should be taken when performing a compare and set or a compare |
| * and exchange operation with such values since the operation may |
| * unexpectedly fail. |
| * There are many possible NaN values that are considered to be |
| * {@code NaN} in Java, although no IEEE 754 floating-point operation |
| * provided by Java can distinguish between them. Operation failure can |
| * occur if the expected or witness value is a NaN value and it is |
| * transformed (perhaps in a platform specific manner) into another NaN |
| * value, and thus has a different bitwise representation (see |
| * {@link Float#intBitsToFloat} or {@link Double#longBitsToDouble} for more |
| * details). |
| * The values {@code -0.0} and {@code +0.0} have different bitwise |
| * representations but are considered equal when using the primitive |
| * {@code ==} operator. Operation failure can occur if, for example, a |
| * numeric algorithm computes an expected value to be say {@code -0.0} |
| * and previously computed the witness value to be say {@code +0.0}. |
| * @param decl the class that declares the static field |
| * @param name the field's name |
| * @param type the field's type, of type {@code T} |
| * @return a VarHandle giving access to a static field |
| * @throws NoSuchFieldException if the field does not exist |
| * @throws IllegalAccessException if access checking fails, or if the field is not {@code static} |
| * @exception SecurityException if a security manager is present and it |
| * <a href="MethodHandles.Lookup.html#secmgr">refuses access</a> |
| * @throws NullPointerException if any argument is null |
| * @since 9 |
| */ |
| public VarHandle findStaticVarHandle(Class<?> decl, String name, Class<?> type) throws NoSuchFieldException, IllegalAccessException { |
| final Field field = findFieldOfType(decl, name, type); |
| final boolean isStatic = true; |
| final boolean performAccessChecks = true; |
| commonFieldChecks(field, decl, type, isStatic, performAccessChecks); |
| return StaticFieldVarHandle.create(field); |
| } |
| // END Android-changed: OpenJDK 9+181 VarHandle API factory method. |
| |
| /** |
| * Produces an early-bound method handle for a non-static method. |
| * The receiver must have a supertype {@code defc} in which a method |
| * of the given name and type is accessible to the lookup class. |
| * The method and all its argument types must be accessible to the lookup object. |
| * The type of the method handle will be that of the method, |
| * without any insertion of an additional receiver parameter. |
| * The given receiver will be bound into the method handle, |
| * so that every call to the method handle will invoke the |
| * requested method on the given receiver. |
| * <p> |
| * The returned method handle will have |
| * {@linkplain MethodHandle#asVarargsCollector variable arity} if and only if |
| * the method's variable arity modifier bit ({@code 0x0080}) is set |
| * <em>and</em> the trailing array argument is not the only argument. |
| * (If the trailing array argument is the only argument, |
| * the given receiver value will be bound to it.) |
| * <p> |
| * This is equivalent to the following code: |
| * <blockquote><pre>{@code |
| import static java.lang.invoke.MethodHandles.*; |
| import static java.lang.invoke.MethodType.*; |
| ... |
| MethodHandle mh0 = lookup().findVirtual(defc, name, type); |
| MethodHandle mh1 = mh0.bindTo(receiver); |
| MethodType mt1 = mh1.type(); |
| if (mh0.isVarargsCollector()) |
| mh1 = mh1.asVarargsCollector(mt1.parameterType(mt1.parameterCount()-1)); |
| return mh1; |
| * }</pre></blockquote> |
| * where {@code defc} is either {@code receiver.getClass()} or a super |
| * type of that class, in which the requested method is accessible |
| * to the lookup class. |
| * (Note that {@code bindTo} does not preserve variable arity.) |
| * @param receiver the object from which the method is accessed |
| * @param name the name of the method |
| * @param type the type of the method, with the receiver argument omitted |
| * @return the desired method handle |
| * @throws NoSuchMethodException if the method does not exist |
| * @throws IllegalAccessException if access checking fails |
| * or if the method's variable arity modifier bit |
| * is set and {@code asVarargsCollector} fails |
| * @exception SecurityException if a security manager is present and it |
| * <a href="MethodHandles.Lookup.html#secmgr">refuses access</a> |
| * @throws NullPointerException if any argument is null |
| * @see MethodHandle#bindTo |
| * @see #findVirtual |
| */ |
| public MethodHandle bind(Object receiver, String name, MethodType type) throws NoSuchMethodException, IllegalAccessException { |
| MethodHandle handle = findVirtual(receiver.getClass(), name, type); |
| MethodHandle adapter = handle.bindTo(receiver); |
| MethodType adapterType = adapter.type(); |
| if (handle.isVarargsCollector()) { |
| adapter = adapter.asVarargsCollector( |
| adapterType.parameterType(adapterType.parameterCount() - 1)); |
| } |
| |
| return adapter; |
| } |
| |
| /** |
| * Makes a <a href="MethodHandleInfo.html#directmh">direct method handle</a> |
| * to <i>m</i>, if the lookup class has permission. |
| * If <i>m</i> is non-static, the receiver argument is treated as an initial argument. |
| * If <i>m</i> is virtual, overriding is respected on every call. |
| * Unlike the Core Reflection API, exceptions are <em>not</em> wrapped. |
| * The type of the method handle will be that of the method, |
| * with the receiver type prepended (but only if it is non-static). |
| * If the method's {@code accessible} flag is not set, |
| * access checking is performed immediately on behalf of the lookup class. |
| * If <i>m</i> is not public, do not share the resulting handle with untrusted parties. |
| * <p> |
| * The returned method handle will have |
| * {@linkplain MethodHandle#asVarargsCollector variable arity} if and only if |
| * the method's variable arity modifier bit ({@code 0x0080}) is set. |
| * <p> |
| * If <i>m</i> is static, and |
| * if the returned method handle is invoked, the method's class will |
| * be initialized, if it has not already been initialized. |
| * @param m the reflected method |
| * @return a method handle which can invoke the reflected method |
| * @throws IllegalAccessException if access checking fails |
| * or if the method's variable arity modifier bit |
| * is set and {@code asVarargsCollector} fails |
| * @throws NullPointerException if the argument is null |
| */ |
| public MethodHandle unreflect(Method m) throws IllegalAccessException { |
| if (m == null) { |
| throw new NullPointerException("m == null"); |
| } |
| |
| MethodType methodType = MethodType.methodType(m.getReturnType(), |
| m.getParameterTypes()); |
| |
| // We should only perform access checks if setAccessible hasn't been called yet. |
| if (!m.isAccessible()) { |
| checkAccess(m.getDeclaringClass(), m.getDeclaringClass(), m.getModifiers(), |
| m.getName()); |
| } |
| |
| if (Modifier.isStatic(m.getModifiers())) { |
| return createMethodHandle(m, MethodHandle.INVOKE_STATIC, methodType); |
| } else { |
| methodType = methodType.insertParameterTypes(0, m.getDeclaringClass()); |
| return createMethodHandle(m, MethodHandle.INVOKE_VIRTUAL, methodType); |
| } |
| } |
| |
| /** |
| * Produces a method handle for a reflected method. |
| * It will bypass checks for overriding methods on the receiver, |
| * <a href="MethodHandles.Lookup.html#equiv">as if called</a> from an {@code invokespecial} |
| * instruction from within the explicitly specified {@code specialCaller}. |
| * The type of the method handle will be that of the method, |
| * with a suitably restricted receiver type prepended. |
| * (The receiver type will be {@code specialCaller} or a subtype.) |
| * If the method's {@code accessible} flag is not set, |
| * access checking is performed immediately on behalf of the lookup class, |
| * as if {@code invokespecial} instruction were being linked. |
| * <p> |
| * Before method resolution, |
| * if the explicitly specified caller class is not identical with the |
| * lookup class, or if this lookup object does not have |
| * <a href="MethodHandles.Lookup.html#privacc">private access</a> |
| * privileges, the access fails. |
| * <p> |
| * The returned method handle will have |
| * {@linkplain MethodHandle#asVarargsCollector variable arity} if and only if |
| * the method's variable arity modifier bit ({@code 0x0080}) is set. |
| * @param m the reflected method |
| * @param specialCaller the class nominally calling the method |
| * @return a method handle which can invoke the reflected method |
| * @throws IllegalAccessException if access checking fails |
| * or if the method's variable arity modifier bit |
| * is set and {@code asVarargsCollector} fails |
| * @throws NullPointerException if any argument is null |
| */ |
| public MethodHandle unreflectSpecial(Method m, Class<?> specialCaller) throws IllegalAccessException { |
| if (m == null) { |
| throw new NullPointerException("m == null"); |
| } |
| |
| if (specialCaller == null) { |
| throw new NullPointerException("specialCaller == null"); |
| } |
| |
| if (!m.isAccessible()) { |
| // Android-changed: Match Java language 9 behavior where unreflectSpecial continues |
| // to require exact caller lookupClass match. |
| checkSpecialCaller(specialCaller, null); |
| } |
| |
| final MethodType methodType = MethodType.methodType(m.getReturnType(), |
| m.getParameterTypes()); |
| return findSpecial(m, methodType, m.getDeclaringClass() /* refc */, specialCaller); |
| } |
| |
| /** |
| * Produces a method handle for a reflected constructor. |
| * The type of the method handle will be that of the constructor, |
| * with the return type changed to the declaring class. |
| * The method handle will perform a {@code newInstance} operation, |
| * creating a new instance of the constructor's class on the |
| * arguments passed to the method handle. |
| * <p> |
| * If the constructor's {@code accessible} flag is not set, |
| * access checking is performed immediately on behalf of the lookup class. |
| * <p> |
| * The returned method handle will have |
| * {@linkplain MethodHandle#asVarargsCollector variable arity} if and only if |
| * the constructor's variable arity modifier bit ({@code 0x0080}) is set. |
| * <p> |
| * If the returned method handle is invoked, the constructor's class will |
| * be initialized, if it has not already been initialized. |
| * @param c the reflected constructor |
| * @return a method handle which can invoke the reflected constructor |
| * @throws IllegalAccessException if access checking fails |
| * or if the method's variable arity modifier bit |
| * is set and {@code asVarargsCollector} fails |
| * @throws NullPointerException if the argument is null |
| */ |
| public MethodHandle unreflectConstructor(Constructor<?> c) throws IllegalAccessException { |
| if (c == null) { |
| throw new NullPointerException("c == null"); |
| } |
| |
| if (!c.isAccessible()) { |
| checkAccess(c.getDeclaringClass(), c.getDeclaringClass(), c.getModifiers(), |
| c.getName()); |
| } |
| |
| return createMethodHandleForConstructor(c); |
| } |
| |
| /** |
| * Produces a method handle giving read access to a reflected field. |
| * The type of the method handle will have a return type of the field's |
| * value type. |
| * If the field is static, the method handle will take no arguments. |
| * Otherwise, its single argument will be the instance containing |
| * the field. |
| * If the field's {@code accessible} flag is not set, |
| * access checking is performed immediately on behalf of the lookup class. |
| * <p> |
| * If the field is static, and |
| * if the returned method handle is invoked, the field's class will |
| * be initialized, if it has not already been initialized. |
| * @param f the reflected field |
| * @return a method handle which can load values from the reflected field |
| * @throws IllegalAccessException if access checking fails |
| * @throws NullPointerException if the argument is null |
| */ |
| public MethodHandle unreflectGetter(Field f) throws IllegalAccessException { |
| return findAccessor(f, f.getDeclaringClass(), f.getType(), |
| Modifier.isStatic(f.getModifiers()) ? MethodHandle.SGET : MethodHandle.IGET, |
| !f.isAccessible() /* performAccessChecks */); |
| } |
| |
| /** |
| * Produces a method handle giving write access to a reflected field. |
| * The type of the method handle will have a void return type. |
| * If the field is static, the method handle will take a single |
| * argument, of the field's value type, the value to be stored. |
| * Otherwise, the two arguments will be the instance containing |
| * the field, and the value to be stored. |
| * If the field's {@code accessible} flag is not set, |
| * access checking is performed immediately on behalf of the lookup class. |
| * <p> |
| * If the field is static, and |
| * if the returned method handle is invoked, the field's class will |
| * be initialized, if it has not already been initialized. |
| * @param f the reflected field |
| * @return a method handle which can store values into the reflected field |
| * @throws IllegalAccessException if access checking fails |
| * @throws NullPointerException if the argument is null |
| */ |
| public MethodHandle unreflectSetter(Field f) throws IllegalAccessException { |
| return findAccessor(f, f.getDeclaringClass(), f.getType(), |
| Modifier.isStatic(f.getModifiers()) ? MethodHandle.SPUT : MethodHandle.IPUT, |
| !f.isAccessible() /* performAccessChecks */); |
| } |
| |
| // BEGIN Android-changed: OpenJDK 9+181 VarHandle API factory method. |
| /** |
| * Produces a VarHandle giving access to a reflected field {@code f} |
| * of type {@code T} declared in a class of type {@code R}. |
| * The VarHandle's variable type is {@code T}. |
| * If the field is non-static the VarHandle has one coordinate type, |
| * {@code R}. Otherwise, the field is static, and the VarHandle has no |
| * coordinate types. |
| * <p> |
| * Access checking is performed immediately on behalf of the lookup |
| * class, regardless of the value of the field's {@code accessible} |
| * flag. |
| * <p> |
| * If the field is static, and if the returned VarHandle is operated |
| * on, the field's declaring class will be initialized, if it has not |
| * already been initialized. |
| * <p> |
| * Certain access modes of the returned VarHandle are unsupported under |
| * the following conditions: |
| * <ul> |
| * <li>if the field is declared {@code final}, then the write, atomic |
| * update, numeric atomic update, and bitwise atomic update access |
| * modes are unsupported. |
| * <li>if the field type is anything other than {@code byte}, |
| * {@code short}, {@code char}, {@code int}, {@code long}, |
| * {@code float}, or {@code double} then numeric atomic update |
| * access modes are unsupported. |
| * <li>if the field type is anything other than {@code boolean}, |
| * {@code byte}, {@code short}, {@code char}, {@code int} or |
| * {@code long} then bitwise atomic update access modes are |
| * unsupported. |
| * </ul> |
| * <p> |
| * If the field is declared {@code volatile} then the returned VarHandle |
| * will override access to the field (effectively ignore the |
| * {@code volatile} declaration) in accordance to its specified |
| * access modes. |
| * <p> |
| * If the field type is {@code float} or {@code double} then numeric |
| * and atomic update access modes compare values using their bitwise |
| * representation (see {@link Float#floatToRawIntBits} and |
| * {@link Double#doubleToRawLongBits}, respectively). |
| * @apiNote |
| * Bitwise comparison of {@code float} values or {@code double} values, |
| * as performed by the numeric and atomic update access modes, differ |
| * from the primitive {@code ==} operator and the {@link Float#equals} |
| * and {@link Double#equals} methods, specifically with respect to |
| * comparing NaN values or comparing {@code -0.0} with {@code +0.0}. |
| * Care should be taken when performing a compare and set or a compare |
| * and exchange operation with such values since the operation may |
| * unexpectedly fail. |
| * There are many possible NaN values that are considered to be |
| * {@code NaN} in Java, although no IEEE 754 floating-point operation |
| * provided by Java can distinguish between them. Operation failure can |
| * occur if the expected or witness value is a NaN value and it is |
| * transformed (perhaps in a platform specific manner) into another NaN |
| * value, and thus has a different bitwise representation (see |
| * {@link Float#intBitsToFloat} or {@link Double#longBitsToDouble} for more |
| * details). |
| * The values {@code -0.0} and {@code +0.0} have different bitwise |
| * representations but are considered equal when using the primitive |
| * {@code ==} operator. Operation failure can occur if, for example, a |
| * numeric algorithm computes an expected value to be say {@code -0.0} |
| * and previously computed the witness value to be say {@code +0.0}. |
| * @param f the reflected field, with a field of type {@code T}, and |
| * a declaring class of type {@code R} |
| * @return a VarHandle giving access to non-static fields or a static |
| * field |
| * @throws IllegalAccessException if access checking fails |
| * @throws NullPointerException if the argument is null |
| * @since 9 |
| */ |
| public VarHandle unreflectVarHandle(Field f) throws IllegalAccessException { |
| final boolean isStatic = Modifier.isStatic(f.getModifiers()); |
| final boolean performAccessChecks = true; |
| commonFieldChecks(f, f.getDeclaringClass(), f.getType(), isStatic, performAccessChecks); |
| return isStatic ? StaticFieldVarHandle.create(f) : FieldVarHandle.create(f); |
| } |
| // END Android-changed: OpenJDK 9+181 VarHandle API factory method. |
| |
| /** |
| * Cracks a <a href="MethodHandleInfo.html#directmh">direct method handle</a> |
| * created by this lookup object or a similar one. |
| * Security and access checks are performed to ensure that this lookup object |
| * is capable of reproducing the target method handle. |
| * This means that the cracking may fail if target is a direct method handle |
| * but was created by an unrelated lookup object. |
| * This can happen if the method handle is <a href="MethodHandles.Lookup.html#callsens">caller sensitive</a> |
| * and was created by a lookup object for a different class. |
| * @param target a direct method handle to crack into symbolic reference components |
| * @return a symbolic reference which can be used to reconstruct this method handle from this lookup object |
| * @exception SecurityException if a security manager is present and it |
| * <a href="MethodHandles.Lookup.html#secmgr">refuses access</a> |
| * @throws IllegalArgumentException if the target is not a direct method handle or if access checking fails |
| * @exception NullPointerException if the target is {@code null} |
| * @see MethodHandleInfo |
| * @since 1.8 |
| */ |
| public MethodHandleInfo revealDirect(MethodHandle target) { |
| MethodHandleImpl directTarget = getMethodHandleImpl(target); |
| MethodHandleInfo info = directTarget.reveal(); |
| |
| try { |
| checkAccess(lookupClass(), info.getDeclaringClass(), info.getModifiers(), |
| info.getName()); |
| } catch (IllegalAccessException exception) { |
| throw new IllegalArgumentException("Unable to access memeber.", exception); |
| } |
| |
| return info; |
| } |
| |
| private boolean hasPrivateAccess() { |
| return (allowedModes & PRIVATE) != 0; |
| } |
| |
| /** Check public/protected/private bits on the symbolic reference class and its member. */ |
| void checkAccess(Class<?> refc, Class<?> defc, int mods, String methName) |
| throws IllegalAccessException { |
| int allowedModes = this.allowedModes; |
| |
| if (Modifier.isProtected(mods) && |
| defc == Object.class && |
| "clone".equals(methName) && |
| refc.isArray()) { |
| // The JVM does this hack also. |
| // (See ClassVerifier::verify_invoke_instructions |
| // and LinkResolver::check_method_accessability.) |
| // Because the JVM does not allow separate methods on array types, |
| // there is no separate method for int[].clone. |
| // All arrays simply inherit Object.clone. |
| // But for access checking logic, we make Object.clone |
| // (normally protected) appear to be public. |
| // Later on, when the DirectMethodHandle is created, |
| // its leading argument will be restricted to the |
| // requested array type. |
| // N.B. The return type is not adjusted, because |
| // that is *not* the bytecode behavior. |
| mods ^= Modifier.PROTECTED | Modifier.PUBLIC; |
| } |
| |
| if (Modifier.isProtected(mods) && Modifier.isConstructor(mods)) { |
| // cannot "new" a protected ctor in a different package |
| mods ^= Modifier.PROTECTED; |
| } |
| |
| if (Modifier.isPublic(mods) && Modifier.isPublic(refc.getModifiers()) && allowedModes != 0) |
| return; // common case |
| int requestedModes = fixmods(mods); // adjust 0 => PACKAGE |
| if ((requestedModes & allowedModes) != 0) { |
| if (VerifyAccess.isMemberAccessible(refc, defc, mods, lookupClass(), allowedModes)) |
| return; |
| } else { |
| // Protected members can also be checked as if they were package-private. |
| if ((requestedModes & PROTECTED) != 0 && (allowedModes & PACKAGE) != 0 |
| && VerifyAccess.isSamePackage(defc, lookupClass())) |
| return; |
| } |
| |
| throwMakeAccessException(accessFailedMessage(refc, defc, mods), this); |
| } |
| |
| String accessFailedMessage(Class<?> refc, Class<?> defc, int mods) { |
| // check the class first: |
| boolean classOK = (Modifier.isPublic(defc.getModifiers()) && |
| (defc == refc || |
| Modifier.isPublic(refc.getModifiers()))); |
| if (!classOK && (allowedModes & PACKAGE) != 0) { |
| classOK = (VerifyAccess.isClassAccessible(defc, lookupClass(), ALL_MODES) && |
| (defc == refc || |
| VerifyAccess.isClassAccessible(refc, lookupClass(), ALL_MODES))); |
| } |
| if (!classOK) |
| return "class is not public"; |
| if (Modifier.isPublic(mods)) |
| return "access to public member failed"; // (how?) |
| if (Modifier.isPrivate(mods)) |
| return "member is private"; |
| if (Modifier.isProtected(mods)) |
| return "member is protected"; |
| return "member is private to package"; |
| } |
| |
| // Android-changed: checkSpecialCaller assumes that ALLOW_NESTMATE_ACCESS = false, |
| // as in upstream OpenJDK. |
| // |
| // private static final boolean ALLOW_NESTMATE_ACCESS = false; |
| |
| // Android-changed: Match java language 9 behavior allowing special access if the reflected |
| // class (called 'refc', the class from which the method is being accessed) is an interface |
| // and is implemented by the caller. |
| private void checkSpecialCaller(Class<?> specialCaller, Class<?> refc) throws IllegalAccessException { |
| // Android-changed: No support for TRUSTED lookups. Also construct the |
| // IllegalAccessException by hand because the upstream code implicitly assumes |
| // that the lookupClass == specialCaller. |
| // |
| // if (allowedModes == TRUSTED) return; |
| boolean isInterfaceLookup = (refc != null && |
| refc.isInterface() && |
| refc.isAssignableFrom(specialCaller)); |
| if (!hasPrivateAccess() || (specialCaller != lookupClass() && !isInterfaceLookup)) { |
| throw new IllegalAccessException("no private access for invokespecial : " |
| + specialCaller + ", from" + this); |
| } |
| } |
| |
| private void throwMakeAccessException(String message, Object from) throws |
| IllegalAccessException{ |
| message = message + ": "+ toString(); |
| if (from != null) message += ", from " + from; |
| throw new IllegalAccessException(message); |
| } |
| |
| private void checkReturnType(Method method, MethodType methodType) |
| throws NoSuchMethodException { |
| if (method.getReturnType() != methodType.rtype()) { |
| throw new NoSuchMethodException(method.getName() + methodType); |
| } |
| } |
| } |
| |
| /** |
| * "Cracks" {@code target} to reveal the underlying {@code MethodHandleImpl}. |
| */ |
| private static MethodHandleImpl getMethodHandleImpl(MethodHandle target) { |
| // Special case : We implement handles to constructors as transformers, |
| // so we must extract the underlying handle from the transformer. |
| if (target instanceof Transformers.Construct) { |
| target = ((Transformers.Construct) target).getConstructorHandle(); |
| } |
| |
| // Special case: Var-args methods are also implemented as Transformers, |
| // so we should get the underlying handle in that case as well. |
| if (target instanceof Transformers.VarargsCollector) { |
| target = target.asFixedArity(); |
| } |
| |
| if (target instanceof MethodHandleImpl) { |
| return (MethodHandleImpl) target; |
| } |
| |
| throw new IllegalArgumentException(target + " is not a direct handle"); |
| } |
| |
| // Android-removed: unsupported @jvms tag in doc-comment. |
| /** |
| * Produces a method handle constructing arrays of a desired type, |
| * as if by the {@code anewarray} bytecode. |
| * The return type of the method handle will be the array type. |
| * The type of its sole argument will be {@code int}, which specifies the size of the array. |
| * |
| * <p> If the returned method handle is invoked with a negative |
| * array size, a {@code NegativeArraySizeException} will be thrown. |
| * |
| * @param arrayClass an array type |
| * @return a method handle which can create arrays of the given type |
| * @throws NullPointerException if the argument is {@code null} |
| * @throws IllegalArgumentException if {@code arrayClass} is not an array type |
| * @see java.lang.reflect.Array#newInstance(Class, int) |
| * @since 9 |
| */ |
| public static |
| MethodHandle arrayConstructor(Class<?> arrayClass) throws IllegalArgumentException { |
| if (!arrayClass.isArray()) { |
| throw newIllegalArgumentException("not an array class: " + arrayClass.getName()); |
| } |
| // Android-changed: transformer based implementation. |
| // MethodHandle ani = MethodHandleImpl.getConstantHandle(MethodHandleImpl.MH_Array_newInstance). |
| // bindTo(arrayClass.getComponentType()); |
| // return ani.asType(ani.type().changeReturnType(arrayClass)) |
| return new Transformers.ArrayConstructor(arrayClass); |
| } |
| |
| // Android-removed: unsupported @jvms tag in doc-comment. |
| /** |
| * Produces a method handle returning the length of an array, |
| * as if by the {@code arraylength} bytecode. |
| * The type of the method handle will have {@code int} as return type, |
| * and its sole argument will be the array type. |
| * |
| * <p> If the returned method handle is invoked with a {@code null} |
| * array reference, a {@code NullPointerException} will be thrown. |
| * |
| * @param arrayClass an array type |
| * @return a method handle which can retrieve the length of an array of the given array type |
| * @throws NullPointerException if the argument is {@code null} |
| * @throws IllegalArgumentException if arrayClass is not an array type |
| * @since 9 |
| */ |
| public static |
| MethodHandle arrayLength(Class<?> arrayClass) throws IllegalArgumentException { |
| // Android-changed: transformer based implementation. |
| // return MethodHandleImpl.makeArrayElementAccessor(arrayClass, MethodHandleImpl.ArrayAccess.LENGTH); |
| if (!arrayClass.isArray()) { |
| throw newIllegalArgumentException("not an array class: " + arrayClass.getName()); |
| } |
| return new Transformers.ArrayLength(arrayClass); |
| } |
| |
| // BEGIN Android-added: method to check if a class is an array. |
| private static void checkClassIsArray(Class<?> c) { |
| if (!c.isArray()) { |
| throw new IllegalArgumentException("Not an array type: " + c); |
| } |
| } |
| |
| private static void checkTypeIsViewable(Class<?> componentType) { |
| if (componentType == short.class || |
| componentType == char.class || |
| componentType == int.class || |
| componentType == long.class || |
| componentType == float.class || |
| componentType == double.class) { |
| return; |
| } |
| throw new UnsupportedOperationException("Component type not supported: " + componentType); |
| } |
| // END Android-added: method to check if a class is an array. |
| |
| /** |
| * Produces a method handle giving read access to elements of an array. |
| * The type of the method handle will have a return type of the array's |
| * element type. Its first argument will be the array type, |
| * and the second will be {@code int}. |
| * @param arrayClass an array type |
| * @return a method handle which can load values from the given array type |
| * @throws NullPointerException if the argument is null |
| * @throws IllegalArgumentException if arrayClass is not an array type |
| */ |
| public static |
| MethodHandle arrayElementGetter(Class<?> arrayClass) throws IllegalArgumentException { |
| checkClassIsArray(arrayClass); |
| final Class<?> componentType = arrayClass.getComponentType(); |
| if (componentType.isPrimitive()) { |
| try { |
| return Lookup.PUBLIC_LOOKUP.findStatic(MethodHandles.class, |
| "arrayElementGetter", |
| MethodType.methodType(componentType, arrayClass, int.class)); |
| } catch (NoSuchMethodException | IllegalAccessException exception) { |
| throw new AssertionError(exception); |
| } |
| } |
| |
| return new Transformers.ReferenceArrayElementGetter(arrayClass); |
| } |
| |
| /** @hide */ public static byte arrayElementGetter(byte[] array, int i) { return array[i]; } |
| /** @hide */ public static boolean arrayElementGetter(boolean[] array, int i) { return array[i]; } |
| /** @hide */ public static char arrayElementGetter(char[] array, int i) { return array[i]; } |
| /** @hide */ public static short arrayElementGetter(short[] array, int i) { return array[i]; } |
| /** @hide */ public static int arrayElementGetter(int[] array, int i) { return array[i]; } |
| /** @hide */ public static long arrayElementGetter(long[] array, int i) { return array[i]; } |
| /** @hide */ public static float arrayElementGetter(float[] array, int i) { return array[i]; } |
| /** @hide */ public static double arrayElementGetter(double[] array, int i) { return array[i]; } |
| |
| /** |
| * Produces a method handle giving write access to elements of an array. |
| * The type of the method handle will have a void return type. |
| * Its last argument will be the array's element type. |
| * The first and second arguments will be the array type and int. |
| * @param arrayClass the class of an array |
| * @return a method handle which can store values into the array type |
| * @throws NullPointerException if the argument is null |
| * @throws IllegalArgumentException if arrayClass is not an array type |
| */ |
| public static |
| MethodHandle arrayElementSetter(Class<?> arrayClass) throws IllegalArgumentException { |
| checkClassIsArray(arrayClass); |
| final Class<?> componentType = arrayClass.getComponentType(); |
| if (componentType.isPrimitive()) { |
| try { |
| return Lookup.PUBLIC_LOOKUP.findStatic(MethodHandles.class, |
| "arrayElementSetter", |
| MethodType.methodType(void.class, arrayClass, int.class, componentType)); |
| } catch (NoSuchMethodException | IllegalAccessException exception) { |
| throw new AssertionError(exception); |
| } |
| } |
| |
| return new Transformers.ReferenceArrayElementSetter(arrayClass); |
| } |
| |
| /** @hide */ |
| public static void arrayElementSetter(byte[] array, int i, byte val) { array[i] = val; } |
| /** @hide */ |
| public static void arrayElementSetter(boolean[] array, int i, boolean val) { array[i] = val; } |
| /** @hide */ |
| public static void arrayElementSetter(char[] array, int i, char val) { array[i] = val; } |
| /** @hide */ |
| public static void arrayElementSetter(short[] array, int i, short val) { array[i] = val; } |
| /** @hide */ |
| public static void arrayElementSetter(int[] array, int i, int val) { array[i] = val; } |
| /** @hide */ |
| public static void arrayElementSetter(long[] array, int i, long val) { array[i] = val; } |
| /** @hide */ |
| public static void arrayElementSetter(float[] array, int i, float val) { array[i] = val; } |
| /** @hide */ |
| public static void arrayElementSetter(double[] array, int i, double val) { array[i] = val; } |
| |
| // BEGIN Android-changed: OpenJDK 9+181 VarHandle API factory methods. |
| /** |
| * Produces a VarHandle giving access to elements of an array of type |
| * {@code arrayClass}. The VarHandle's variable type is the component type |
| * of {@code arrayClass} and the list of coordinate types is |
| * {@code (arrayClass, int)}, where the {@code int} coordinate type |
| * corresponds to an argument that is an index into an array. |
| * <p> |
| * Certain access modes of the returned VarHandle are unsupported under |
| * the following conditions: |
| * <ul> |
| * <li>if the component type is anything other than {@code byte}, |
| * {@code short}, {@code char}, {@code int}, {@code long}, |
| * {@code float}, or {@code double} then numeric atomic update access |
| * modes are unsupported. |
| * <li>if the field type is anything other than {@code boolean}, |
| * {@code byte}, {@code short}, {@code char}, {@code int} or |
| * {@code long} then bitwise atomic update access modes are |
| * unsupported. |
| * </ul> |
| * <p> |
| * If the component type is {@code float} or {@code double} then numeric |
| * and atomic update access modes compare values using their bitwise |
| * representation (see {@link Float#floatToRawIntBits} and |
| * {@link Double#doubleToRawLongBits}, respectively). |
| * @apiNote |
| * Bitwise comparison of {@code float} values or {@code double} values, |
| * as performed by the numeric and atomic update access modes, differ |
| * from the primitive {@code ==} operator and the {@link Float#equals} |
| * and {@link Double#equals} methods, specifically with respect to |
| * comparing NaN values or comparing {@code -0.0} with {@code +0.0}. |
| * Care should be taken when performing a compare and set or a compare |
| * and exchange operation with such values since the operation may |
| * unexpectedly fail. |
| * There are many possible NaN values that are considered to be |
| * {@code NaN} in Java, although no IEEE 754 floating-point operation |
| * provided by Java can distinguish between them. Operation failure can |
| * occur if the expected or witness value is a NaN value and it is |
| * transformed (perhaps in a platform specific manner) into another NaN |
| * value, and thus has a different bitwise representation (see |
| * {@link Float#intBitsToFloat} or {@link Double#longBitsToDouble} for more |
| * details). |
| * The values {@code -0.0} and {@code +0.0} have different bitwise |
| * representations but are considered equal when using the primitive |
| * {@code ==} operator. Operation failure can occur if, for example, a |
| * numeric algorithm computes an expected value to be say {@code -0.0} |
| * and previously computed the witness value to be say {@code +0.0}. |
| * @param arrayClass the class of an array, of type {@code T[]} |
| * @return a VarHandle giving access to elements of an array |
| * @throws NullPointerException if the arrayClass is null |
| * @throws IllegalArgumentException if arrayClass is not an array type |
| * @since 9 |
| */ |
| public static |
| VarHandle arrayElementVarHandle(Class<?> arrayClass) throws IllegalArgumentException { |
| checkClassIsArray(arrayClass); |
| return ArrayElementVarHandle.create(arrayClass); |
| } |
| |
| /** |
| * Produces a VarHandle giving access to elements of a {@code byte[]} array |
| * viewed as if it were a different primitive array type, such as |
| * {@code int[]} or {@code long[]}. |
| * The VarHandle's variable type is the component type of |
| * {@code viewArrayClass} and the list of coordinate types is |
| * {@code (byte[], int)}, where the {@code int} coordinate type |
| * corresponds to an argument that is an index into a {@code byte[]} array. |
| * The returned VarHandle accesses bytes at an index in a {@code byte[]} |
| * array, composing bytes to or from a value of the component type of |
| * {@code viewArrayClass} according to the given endianness. |
| * <p> |
| * The supported component types (variables types) are {@code short}, |
| * {@code char}, {@code int}, {@code long}, {@code float} and |
| * {@code double}. |
| * <p> |
| * Access of bytes at a given index will result in an |
| * {@code IndexOutOfBoundsException} if the index is less than {@code 0} |
| * or greater than the {@code byte[]} array length minus the size (in bytes) |
| * of {@code T}. |
| * <p> |
| * Access of bytes at an index may be aligned or misaligned for {@code T}, |
| * with respect to the underlying memory address, {@code A} say, associated |
| * with the array and index. |
| * If access is misaligned then access for anything other than the |
| * {@code get} and {@code set} access modes will result in an |
| * {@code IllegalStateException}. In such cases atomic access is only |
| * guaranteed with respect to the largest power of two that divides the GCD |
| * of {@code A} and the size (in bytes) of {@code T}. |
| * If access is aligned then following access modes are supported and are |
| * guaranteed to support atomic access: |
| * <ul> |
| * <li>read write access modes for all {@code T}, with the exception of |
| * access modes {@code get} and {@code set} for {@code long} and |
| * {@code double} on 32-bit platforms. |
| * <li>atomic update access modes for {@code int}, {@code long}, |
| * {@code float} or {@code double}. |
| * (Future major platform releases of the JDK may support additional |
| * types for certain currently unsupported access modes.) |
| * <li>numeric atomic update access modes for {@code int} and {@code long}. |
| * (Future major platform releases of the JDK may support additional |
| * numeric types for certain currently unsupported access modes.) |
| * <li>bitwise atomic update access modes for {@code int} and {@code long}. |
| * (Future major platform releases of the JDK may support additional |
| * numeric types for certain currently unsupported access modes.) |
| * </ul> |
| * <p> |
| * Misaligned access, and therefore atomicity guarantees, may be determined |
| * for {@code byte[]} arrays without operating on a specific array. Given |
| * an {@code index}, {@code T} and it's corresponding boxed type, |
| * {@code T_BOX}, misalignment may be determined as follows: |
| * <pre>{@code |
| * int sizeOfT = T_BOX.BYTES; // size in bytes of T |
| * int misalignedAtZeroIndex = ByteBuffer.wrap(new byte[0]). |
| * alignmentOffset(0, sizeOfT); |
| * int misalignedAtIndex = (misalignedAtZeroIndex + index) % sizeOfT; |
| * boolean isMisaligned = misalignedAtIndex != 0; |
| * }</pre> |
| * <p> |
| * If the variable type is {@code float} or {@code double} then atomic |
| * update access modes compare values using their bitwise representation |
| * (see {@link Float#floatToRawIntBits} and |
| * {@link Double#doubleToRawLongBits}, respectively). |
| * @param viewArrayClass the view array class, with a component type of |
| * type {@code T} |
| * @param byteOrder the endianness of the view array elements, as |
| * stored in the underlying {@code byte} array |
| * @return a VarHandle giving access to elements of a {@code byte[]} array |
| * viewed as if elements corresponding to the components type of the view |
| * array class |
| * @throws NullPointerException if viewArrayClass or byteOrder is null |
| * @throws IllegalArgumentException if viewArrayClass is not an array type |
| * @throws UnsupportedOperationException if the component type of |
| * viewArrayClass is not supported as a variable type |
| * @since 9 |
| */ |
| public static |
| VarHandle byteArrayViewVarHandle(Class<?> viewArrayClass, |
| ByteOrder byteOrder) throws IllegalArgumentException { |
| checkClassIsArray(viewArrayClass); |
| checkTypeIsViewable(viewArrayClass.getComponentType()); |
| return ByteArrayViewVarHandle.create(viewArrayClass, byteOrder); |
| } |
| |
| /** |
| * Produces a VarHandle giving access to elements of a {@code ByteBuffer} |
| * viewed as if it were an array of elements of a different primitive |
| * component type to that of {@code byte}, such as {@code int[]} or |
| * {@code long[]}. |
| * The VarHandle's variable type is the component type of |
| * {@code viewArrayClass} and the list of coordinate types is |
| * {@code (ByteBuffer, int)}, where the {@code int} coordinate type |
| * corresponds to an argument that is an index into a {@code byte[]} array. |
| * The returned VarHandle accesses bytes at an index in a |
| * {@code ByteBuffer}, composing bytes to or from a value of the component |
| * type of {@code viewArrayClass} according to the given endianness. |
| * <p> |
| * The supported component types (variables types) are {@code short}, |
| * {@code char}, {@code int}, {@code long}, {@code float} and |
| * {@code double}. |
| * <p> |
| * Access will result in a {@code ReadOnlyBufferException} for anything |
| * other than the read access modes if the {@code ByteBuffer} is read-only. |
| * <p> |
| * Access of bytes at a given index will result in an |
| * {@code IndexOutOfBoundsException} if the index is less than {@code 0} |
| * or greater than the {@code ByteBuffer} limit minus the size (in bytes) of |
| * {@code T}. |
| * <p> |
| * Access of bytes at an index may be aligned or misaligned for {@code T}, |
| * with respect to the underlying memory address, {@code A} say, associated |
| * with the {@code ByteBuffer} and index. |
| * If access is misaligned then access for anything other than the |
| * {@code get} and {@code set} access modes will result in an |
| * {@code IllegalStateException}. In such cases atomic access is only |
| * guaranteed with respect to the largest power of two that divides the GCD |
| * of {@code A} and the size (in bytes) of {@code T}. |
| * If access is aligned then following access modes are supported and are |
| * guaranteed to support atomic access: |
| * <ul> |
| * <li>read write access modes for all {@code T}, with the exception of |
| * access modes {@code get} and {@code set} for {@code long} and |
| * {@code double} on 32-bit platforms. |
| * <li>atomic update access modes for {@code int}, {@code long}, |
| * {@code float} or {@code double}. |
| * (Future major platform releases of the JDK may support additional |
| * types for certain currently unsupported access modes.) |
| * <li>numeric atomic update access modes for {@code int} and {@code long}. |
| * (Future major platform releases of the JDK may support additional |
| * numeric types for certain currently unsupported access modes.) |
| * <li>bitwise atomic update access modes for {@code int} and {@code long}. |
| * (Future major platform releases of the JDK may support additional |
| * numeric types for certain currently unsupported access modes.) |
| * </ul> |
| * <p> |
| * Misaligned access, and therefore atomicity guarantees, may be determined |
| * for a {@code ByteBuffer}, {@code bb} (direct or otherwise), an |
| * {@code index}, {@code T} and it's corresponding boxed type, |
| * {@code T_BOX}, as follows: |
| * <pre>{@code |
| * int sizeOfT = T_BOX.BYTES; // size in bytes of T |
| * ByteBuffer bb = ... |
| * int misalignedAtIndex = bb.alignmentOffset(index, sizeOfT); |
| * boolean isMisaligned = misalignedAtIndex != 0; |
| * }</pre> |
| * <p> |
| * If the variable type is {@code float} or {@code double} then atomic |
| * update access modes compare values using their bitwise representation |
| * (see {@link Float#floatToRawIntBits} and |
| * {@link Double#doubleToRawLongBits}, respectively). |
| * @param viewArrayClass the view array class, with a component type of |
| * type {@code T} |
| * @param byteOrder the endianness of the view array elements, as |
| * stored in the underlying {@code ByteBuffer} (Note this overrides the |
| * endianness of a {@code ByteBuffer}) |
| * @return a VarHandle giving access to elements of a {@code ByteBuffer} |
| * viewed as if elements corresponding to the components type of the view |
| * array class |
| * @throws NullPointerException if viewArrayClass or byteOrder is null |
| * @throws IllegalArgumentException if viewArrayClass is not an array type |
| * @throws UnsupportedOperationException if the component type of |
| * viewArrayClass is not supported as a variable type |
| * @since 9 |
| */ |
| public static |
| VarHandle byteBufferViewVarHandle(Class<?> viewArrayClass, |
| ByteOrder byteOrder) throws IllegalArgumentException { |
| checkClassIsArray(viewArrayClass); |
| checkTypeIsViewable(viewArrayClass.getComponentType()); |
| return ByteBufferViewVarHandle.create(viewArrayClass, byteOrder); |
| } |
| // END Android-changed: OpenJDK 9+181 VarHandle API factory methods. |
| |
| /// method handle invocation (reflective style) |
| |
| /** |
| * Produces a method handle which will invoke any method handle of the |
| * given {@code type}, with a given number of trailing arguments replaced by |
| * a single trailing {@code Object[]} array. |
| * The resulting invoker will be a method handle with the following |
| * arguments: |
| * <ul> |
| * <li>a single {@code MethodHandle} target |
| * <li>zero or more leading values (counted by {@code leadingArgCount}) |
| * <li>an {@code Object[]} array containing trailing arguments |
| * </ul> |
| * <p> |
| * The invoker will invoke its target like a call to {@link MethodHandle#invoke invoke} with |
| * the indicated {@code type}. |
| * That is, if the target is exactly of the given {@code type}, it will behave |
| * like {@code invokeExact}; otherwise it behave as if {@link MethodHandle#asType asType} |
| * is used to convert the target to the required {@code type}. |
| * <p> |
| * The type of the returned invoker will not be the given {@code type}, but rather |
| * will have all parameters except the first {@code leadingArgCount} |
| * replaced by a single array of type {@code Object[]}, which will be |
| * the final parameter. |
| * <p> |
| * Before invoking its target, the invoker will spread the final array, apply |
| * reference casts as necessary, and unbox and widen primitive arguments. |
| * If, when the invoker is called, the supplied array argument does |
| * not have the correct number of elements, the invoker will throw |
| * an {@link IllegalArgumentException} instead of invoking the target. |
| * <p> |
| * This method is equivalent to the following code (though it may be more efficient): |
| * <blockquote><pre>{@code |
| MethodHandle invoker = MethodHandles.invoker(type); |
| int spreadArgCount = type.parameterCount() - leadingArgCount; |
| invoker = invoker.asSpreader(Object[].class, spreadArgCount); |
| return invoker; |
| * }</pre></blockquote> |
| * This method throws no reflective or security exceptions. |
| * @param type the desired target type |
| * @param leadingArgCount number of fixed arguments, to be passed unchanged to the target |
| * @return a method handle suitable for invoking any method handle of the given type |
| * @throws NullPointerException if {@code type} is null |
| * @throws IllegalArgumentException if {@code leadingArgCount} is not in |
| * the range from 0 to {@code type.parameterCount()} inclusive, |
| * or if the resulting method handle's type would have |
| * <a href="MethodHandle.html#maxarity">too many parameters</a> |
| */ |
| static public |
| MethodHandle spreadInvoker(MethodType type, int leadingArgCount) { |
| if (leadingArgCount < 0 || leadingArgCount > type.parameterCount()) |
| throw newIllegalArgumentException("bad argument count", leadingArgCount); |
| |
| MethodHandle invoker = MethodHandles.invoker(type); |
| int spreadArgCount = type.parameterCount() - leadingArgCount; |
| invoker = invoker.asSpreader(Object[].class, spreadArgCount); |
| return invoker; |
| } |
| |
| /** |
| * Produces a special <em>invoker method handle</em> which can be used to |
| * invoke any method handle of the given type, as if by {@link MethodHandle#invokeExact invokeExact}. |
| * The resulting invoker will have a type which is |
| * exactly equal to the desired type, except that it will accept |
| * an additional leading argument of type {@code MethodHandle}. |
| * <p> |
| * This method is equivalent to the following code (though it may be more efficient): |
| * {@code publicLookup().findVirtual(MethodHandle.class, "invokeExact", type)} |
| * |
| * <p style="font-size:smaller;"> |
| * <em>Discussion:</em> |
| * Invoker method handles can be useful when working with variable method handles |
| * of unknown types. |
| * For example, to emulate an {@code invokeExact} call to a variable method |
| * handle {@code M}, extract its type {@code T}, |
| * look up the invoker method {@code X} for {@code T}, |
| * and call the invoker method, as {@code X.invoke(T, A...)}. |
| * (It would not work to call {@code X.invokeExact}, since the type {@code T} |
| * is unknown.) |
| * If spreading, collecting, or other argument transformations are required, |
| * they can be applied once to the invoker {@code X} and reused on many {@code M} |
| * method handle values, as long as they are compatible with the type of {@code X}. |
| * <p style="font-size:smaller;"> |
| * <em>(Note: The invoker method is not available via the Core Reflection API. |
| * An attempt to call {@linkplain java.lang.reflect.Method#invoke java.lang.reflect.Method.invoke} |
| * on the declared {@code invokeExact} or {@code invoke} method will raise an |
| * {@link java.lang.UnsupportedOperationException UnsupportedOperationException}.)</em> |
| * <p> |
| * This method throws no reflective or security exceptions. |
| * @param type the desired target type |
| * @return a method handle suitable for invoking any method handle of the given type |
| * @throws IllegalArgumentException if the resulting method handle's type would have |
| * <a href="MethodHandle.html#maxarity">too many parameters</a> |
| */ |
| static public |
| MethodHandle exactInvoker(MethodType type) { |
| return new Transformers.Invoker(type, true /* isExactInvoker */); |
| } |
| |
| /** |
| * Produces a special <em>invoker method handle</em> which can be used to |
| * invoke any method handle compatible with the given type, as if by {@link MethodHandle#invoke invoke}. |
| * The resulting invoker will have a type which is |
| * exactly equal to the desired type, except that it will accept |
| * an additional leading argument of type {@code MethodHandle}. |
| * <p> |
| * Before invoking its target, if the target differs from the expected type, |
| * the invoker will apply reference casts as |
| * necessary and box, unbox, or widen primitive values, as if by {@link MethodHandle#asType asType}. |
| * Similarly, the return value will be converted as necessary. |
| * If the target is a {@linkplain MethodHandle#asVarargsCollector variable arity method handle}, |
| * the required arity conversion will be made, again as if by {@link MethodHandle#asType asType}. |
| * <p> |
| * This method is equivalent to the following code (though it may be more efficient): |
| * {@code publicLookup().findVirtual(MethodHandle.class, "invoke", type)} |
| * <p style="font-size:smaller;"> |
| * <em>Discussion:</em> |
| * A {@linkplain MethodType#genericMethodType general method type} is one which |
| * mentions only {@code Object} arguments and return values. |
| * An invoker for such a type is capable of calling any method handle |
| * of the same arity as the general type. |
| * <p style="font-size:smaller;"> |
| * <em>(Note: The invoker method is not available via the Core Reflection API. |
| * An attempt to call {@linkplain java.lang.reflect.Method#invoke java.lang.reflect.Method.invoke} |
| * on the declared {@code invokeExact} or {@code invoke} method will raise an |
| * {@link java.lang.UnsupportedOperationException UnsupportedOperationException}.)</em> |
| * <p> |
| * This method throws no reflective or security exceptions. |
| * @param type the desired target type |
| * @return a method handle suitable for invoking any method handle convertible to the given type |
| * @throws IllegalArgumentException if the resulting method handle's type would have |
| * <a href="MethodHandle.html#maxarity">too many parameters</a> |
| */ |
| static public |
| MethodHandle invoker(MethodType type) { |
| return new Transformers.Invoker(type, false /* isExactInvoker */); |
| } |
| |
| // BEGIN Android-added: resolver for VarHandle accessor methods. |
| static private MethodHandle methodHandleForVarHandleAccessor(VarHandle.AccessMode accessMode, |
| MethodType type, |
| boolean isExactInvoker) { |
| Class<?> refc = VarHandle.class; |
| Method method; |
| try { |
| method = refc.getDeclaredMethod(accessMode.methodName(), Object[].class); |
| } catch (NoSuchMethodException e) { |
| throw new InternalError("No method for AccessMode " + accessMode, e); |
| } |
| MethodType methodType = type.insertParameterTypes(0, VarHandle.class); |
| int kind = isExactInvoker ? MethodHandle.INVOKE_VAR_HANDLE_EXACT |
| : MethodHandle.INVOKE_VAR_HANDLE; |
| return new MethodHandleImpl(method.getArtMethod(), kind, methodType); |
| } |
| // END Android-added: resolver for VarHandle accessor methods. |
| |
| /** |
| * Produces a special <em>invoker method handle</em> which can be used to |
| * invoke a signature-polymorphic access mode method on any VarHandle whose |
| * associated access mode type is compatible with the given type. |
| * The resulting invoker will have a type which is exactly equal to the |
| * desired given type, except that it will accept an additional leading |
| * argument of type {@code VarHandle}. |
| * |
| * @param accessMode the VarHandle access mode |
| * @param type the desired target type |
| * @return a method handle suitable for invoking an access mode method of |
| * any VarHandle whose access mode type is of the given type. |
| * @since 9 |
| */ |
| static public |
| MethodHandle varHandleExactInvoker(VarHandle.AccessMode accessMode, MethodType type) { |
| return methodHandleForVarHandleAccessor(accessMode, type, true /* isExactInvoker */); |
| } |
| |
| /** |
| * Produces a special <em>invoker method handle</em> which can be used to |
| * invoke a signature-polymorphic access mode method on any VarHandle whose |
| * associated access mode type is compatible with the given type. |
| * The resulting invoker will have a type which is exactly equal to the |
| * desired given type, except that it will accept an additional leading |
| * argument of type {@code VarHandle}. |
| * <p> |
| * Before invoking its target, if the access mode type differs from the |
| * desired given type, the invoker will apply reference casts as necessary |
| * and box, unbox, or widen primitive values, as if by |
| * {@link MethodHandle#asType asType}. Similarly, the return value will be |
| * converted as necessary. |
| * <p> |
| * This method is equivalent to the following code (though it may be more |
| * efficient): {@code publicLookup().findVirtual(VarHandle.class, accessMode.name(), type)} |
| * |
| * @param accessMode the VarHandle access mode |
| * @param type the desired target type |
| * @return a method handle suitable for invoking an access mode method of |
| * any VarHandle whose access mode type is convertible to the given |
| * type. |
| * @since 9 |
| */ |
| static public |
| MethodHandle varHandleInvoker(VarHandle.AccessMode accessMode, MethodType type) { |
| return methodHandleForVarHandleAccessor(accessMode, type, false /* isExactInvoker */); |
| } |
| |
| // Android-changed: Basic invokers are not supported. |
| // |
| // static /*non-public*/ |
| // MethodHandle basicInvoker(MethodType type) { |
| // return type.invokers().basicInvoker(); |
| // } |
| |
| /// method handle modification (creation from other method handles) |
| |
| /** |
| * Produces a method handle which adapts the type of the |
| * given method handle to a new type by pairwise argument and return type conversion. |
| * The original type and new type must have the same number of arguments. |
| * The resulting method handle is guaranteed to report a type |
| * which is equal to the desired new type. |
| * <p> |
| * If the original type and new type are equal, returns target. |
| * <p> |
| * The same conversions are allowed as for {@link MethodHandle#asType MethodHandle.asType}, |
| * and some additional conversions are also applied if those conversions fail. |
| * Given types <em>T0</em>, <em>T1</em>, one of the following conversions is applied |
| * if possible, before or instead of any conversions done by {@code asType}: |
| * <ul> |
| * <li>If <em>T0</em> and <em>T1</em> are references, and <em>T1</em> is an interface type, |
| * then the value of type <em>T0</em> is passed as a <em>T1</em> without a cast. |
| * (This treatment of interfaces follows the usage of the bytecode verifier.) |
| * <li>If <em>T0</em> is boolean and <em>T1</em> is another primitive, |
| * the boolean is converted to a byte value, 1 for true, 0 for false. |
| * (This treatment follows the usage of the bytecode verifier.) |
| * <li>If <em>T1</em> is boolean and <em>T0</em> is another primitive, |
| * <em>T0</em> is converted to byte via Java casting conversion (JLS 5.5), |
| * and the low order bit of the result is tested, as if by {@code (x & 1) != 0}. |
| * <li>If <em>T0</em> and <em>T1</em> are primitives other than boolean, |
| * then a Java casting conversion (JLS 5.5) is applied. |
| * (Specifically, <em>T0</em> will convert to <em>T1</em> by |
| * widening and/or narrowing.) |
| * <li>If <em>T0</em> is a reference and <em>T1</em> a primitive, an unboxing |
| * conversion will be applied at runtime, possibly followed |
| * by a Java casting conversion (JLS 5.5) on the primitive value, |
| * possibly followed by a conversion from byte to boolean by testing |
| * the low-order bit. |
| * <li>If <em>T0</em> is a reference and <em>T1</em> a primitive, |
| * and if the reference is null at runtime, a zero value is introduced. |
| * </ul> |
| * @param target the method handle to invoke after arguments are retyped |
| * @param newType the expected type of the new method handle |
| * @return a method handle which delegates to the target after performing |
| * any necessary argument conversions, and arranges for any |
| * necessary return value conversions |
| * @throws NullPointerException if either argument is null |
| * @throws WrongMethodTypeException if the conversion cannot be made |
| * @see MethodHandle#asType |
| */ |
| public static |
| MethodHandle explicitCastArguments(MethodHandle target, MethodType newType) { |
| explicitCastArgumentsChecks(target, newType); |
| // use the asTypeCache when possible: |
| MethodType oldType = target.type(); |
| if (oldType == newType) return target; |
| if (oldType.explicitCastEquivalentToAsType(newType)) { |
| if (Transformers.Transformer.class.isAssignableFrom(target.getClass())) { |
| // The StackFrameReader and StackFrameWriter used to perform transforms on |
| // EmulatedStackFrames (in Transformers.java) do not how to perform asType() |
| // conversions, but we know here that an explicit cast transform is the same as |
| // having called asType() on the method handle. |
| return new Transformers.ExplicitCastArguments(target.asFixedArity(), newType); |
| } else { |
| // Runtime will perform asType() conversion during invocation. |
| return target.asFixedArity().asType(newType); |
| } |
| } |
| return new Transformers.ExplicitCastArguments(target, newType); |
| } |
| |
| private static void explicitCastArgumentsChecks(MethodHandle target, MethodType newType) { |
| if (target.type().parameterCount() != newType.parameterCount()) { |
| throw new WrongMethodTypeException("cannot explicitly cast " + target + |
| " to " + newType); |
| } |
| } |
| |
| /** |
| * Produces a method handle which adapts the calling sequence of the |
| * given method handle to a new type, by reordering the arguments. |
| * The resulting method handle is guaranteed to report a type |
| * which is equal to the desired new type. |
| * <p> |
| * The given array controls the reordering. |
| * Call {@code #I} the number of incoming parameters (the value |
| * {@code newType.parameterCount()}, and call {@code #O} the number |
| * of outgoing parameters (the value {@code target.type().parameterCount()}). |
| * Then the length of the reordering array must be {@code #O}, |
| * and each element must be a non-negative number less than {@code #I}. |
| * For every {@code N} less than {@code #O}, the {@code N}-th |
| * outgoing argument will be taken from the {@code I}-th incoming |
| * argument, where {@code I} is {@code reorder[N]}. |
| * <p> |
| * No argument or return value conversions are applied. |
| * The type of each incoming argument, as determined by {@code newType}, |
| * must be identical to the type of the corresponding outgoing parameter |
| * or parameters in the target method handle. |
| * The return type of {@code newType} must be identical to the return |
| * type of the original target. |
| * <p> |
| * The reordering array need not specify an actual permutation. |
| * An incoming argument will be duplicated if its index appears |
| * more than once in the array, and an incoming argument will be dropped |
| * if its index does not appear in the array. |
| * As in the case of {@link #dropArguments(MethodHandle,int,List) dropArguments}, |
| * incoming arguments which are not mentioned in the reordering array |
| * are may be any type, as determined only by {@code newType}. |
| * <blockquote><pre>{@code |
| import static java.lang.invoke.MethodHandles.*; |
| import static java.lang.invoke.MethodType.*; |
| ... |
| MethodType intfn1 = methodType(int.class, int.class); |
| MethodType intfn2 = methodType(int.class, int.class, int.class); |
| MethodHandle sub = ... (int x, int y) -> (x-y) ...; |
| assert(sub.type().equals(intfn2)); |
| MethodHandle sub1 = permuteArguments(sub, intfn2, 0, 1); |
| MethodHandle rsub = permuteArguments(sub, intfn2, 1, 0); |
| assert((int)rsub.invokeExact(1, 100) == 99); |
| MethodHandle add = ... (int x, int y) -> (x+y) ...; |
| assert(add.type().equals(intfn2)); |
| MethodHandle twice = permuteArguments(add, intfn1, 0, 0); |
| assert(twice.type().equals(intfn1)); |
| assert((int)twice.invokeExact(21) == 42); |
| * }</pre></blockquote> |
| * @param target the method handle to invoke after arguments are reordered |
| * @param newType the expected type of the new method handle |
| * @param reorder an index array which controls the reordering |
| * @return a method handle which delegates to the target after it |
| * drops unused arguments and moves and/or duplicates the other arguments |
| * @throws NullPointerException if any argument is null |
| * @throws IllegalArgumentException if the index array length is not equal to |
| * the arity of the target, or if any index array element |
| * not a valid index for a parameter of {@code newType}, |
| * or if two corresponding parameter types in |
| * {@code target.type()} and {@code newType} are not identical, |
| */ |
| public static |
| MethodHandle permuteArguments(MethodHandle target, MethodType newType, int... reorder) { |
| reorder = reorder.clone(); // get a private copy |
| MethodType oldType = target.type(); |
| permuteArgumentChecks(reorder, newType, oldType); |
| |
| return new Transformers.PermuteArguments(newType, target, reorder); |
| } |
| |
| // Android-changed: findFirstDupOrDrop is unused and removed. |
| // private static int findFirstDupOrDrop(int[] reorder, int newArity); |
| |
| private static boolean permuteArgumentChecks(int[] reorder, MethodType newType, MethodType oldType) { |
| if (newType.returnType() != oldType.returnType()) |
| throw newIllegalArgumentException("return types do not match", |
| oldType, newType); |
| if (reorder.length == oldType.parameterCount()) { |
| int limit = newType.parameterCount(); |
| boolean bad = false; |
| for (int j = 0; j < reorder.length; j++) { |
| int i = reorder[j]; |
| if (i < 0 || i >= limit) { |
| bad = true; break; |
| } |
| Class<?> src = newType.parameterType(i); |
| Class<?> dst = oldType.parameterType(j); |
| if (src != dst) |
| throw newIllegalArgumentException("parameter types do not match after reorder", |
| oldType, newType); |
| } |
| if (!bad) return true; |
| } |
| throw newIllegalArgumentException("bad reorder array: "+Arrays.toString(reorder)); |
| } |
| |
| /** |
| * Produces a method handle of the requested return type which returns the given |
| * constant value every time it is invoked. |
| * <p> |
| * Before the method handle is returned, the passed-in value is converted to the requested type. |
| * If the requested type is primitive, widening primitive conversions are attempted, |
| * else reference conversions are attempted. |
| * <p>The returned method handle is equivalent to {@code identity(type).bindTo(value)}. |
| * @param type the return type of the desired method handle |
| * @param value the value to return |
| * @return a method handle of the given return type and no arguments, which always returns the given value |
| * @throws NullPointerException if the {@code type} argument is null |
| * @throws ClassCastException if the value cannot be converted to the required return type |
| * @throws IllegalArgumentException if the given type is {@code void.class} |
| */ |
| public static |
| MethodHandle constant(Class<?> type, Object value) { |
| if (type.isPrimitive()) { |
| if (type == void.class) |
| throw newIllegalArgumentException("void type"); |
| Wrapper w = Wrapper.forPrimitiveType(type); |
| value = w.convert(value, type); |
| if (w.zero().equals(value)) |
| return zero(w, type); |
| return insertArguments(identity(type), 0, value); |
| } else { |
| if (value == null) |
| return zero(Wrapper.OBJECT, type); |
| return identity(type).bindTo(value); |
| } |
| } |
| |
| /** |
| * Produces a method handle which returns its sole argument when invoked. |
| * @param type the type of the sole parameter and return value of the desired method handle |
| * @return a unary method handle which accepts and returns the given type |
| * @throws NullPointerException if the argument is null |
| * @throws IllegalArgumentException if the given type is {@code void.class} |
| */ |
| public static |
| MethodHandle identity(Class<?> type) { |
| // Android-added: explicit non-null check. |
| Objects.requireNonNull(type); |
| Wrapper btw = (type.isPrimitive() ? Wrapper.forPrimitiveType(type) : Wrapper.OBJECT); |
| int pos = btw.ordinal(); |
| MethodHandle ident = IDENTITY_MHS[pos]; |
| if (ident == null) { |
| ident = setCachedMethodHandle(IDENTITY_MHS, pos, makeIdentity(btw.primitiveType())); |
| } |
| if (ident.type().returnType() == type) |
| return ident; |
| // something like identity(Foo.class); do not bother to intern these |
| assert (btw == Wrapper.OBJECT); |
| return makeIdentity(type); |
| } |
| |
| /** |
| * Produces a constant method handle of the requested return type which |
| * returns the default value for that type every time it is invoked. |
| * The resulting constant method handle will have no side effects. |
| * <p>The returned method handle is equivalent to {@code empty(methodType(type))}. |
| * It is also equivalent to {@code explicitCastArguments(constant(Object.class, null), methodType(type))}, |
| * since {@code explicitCastArguments} converts {@code null} to default values. |
| * @param type the expected return type of the desired method handle |
| * @return a constant method handle that takes no arguments |
| * and returns the default value of the given type (or void, if the type is void) |
| * @throws NullPointerException if the argument is null |
| * @see MethodHandles#constant |
| * @see MethodHandles#empty |
| * @see MethodHandles#explicitCastArguments |
| * @since 9 |
| */ |
| public static MethodHandle zero(Class<?> type) { |
| Objects.requireNonNull(type); |
| return type.isPrimitive() ? zero(Wrapper.forPrimitiveType(type), type) : zero(Wrapper.OBJECT, type); |
| } |
| |
| private static MethodHandle identityOrVoid(Class<?> type) { |
| return type == void.class ? zero(type) : identity(type); |
| } |
| |
| /** |
| * Produces a method handle of the requested type which ignores any arguments, does nothing, |
| * and returns a suitable default depending on the return type. |
| * That is, it returns a zero primitive value, a {@code null}, or {@code void}. |
| * <p>The returned method handle is equivalent to |
| * {@code dropArguments(zero(type.returnType()), 0, type.parameterList())}. |
| * |
| * @apiNote Given a predicate and target, a useful "if-then" construct can be produced as |
| * {@code guardWithTest(pred, target, empty(target.type())}. |
| * @param type the type of the desired method handle |
| * @return a constant method handle of the given type, which returns a default value of the given return type |
| * @throws NullPointerException if the argument is null |
| * @see MethodHandles#zero |
| * @see MethodHandles#constant |
| * @since 9 |
| */ |
| public static MethodHandle empty(MethodType type) { |
| Objects.requireNonNull(type); |
| return dropArguments(zero(type.returnType()), 0, type.parameterList()); |
| } |
| |
| private static final MethodHandle[] IDENTITY_MHS = new MethodHandle[Wrapper.COUNT]; |
| private static MethodHandle makeIdentity(Class<?> ptype) { |
| // Android-changed: Android implementation using identity() functions and transformers. |
| // MethodType mtype = methodType(ptype, ptype); |
| // LambdaForm lform = LambdaForm.identityForm(BasicType.basicType(ptype)); |
| // return MethodHandleImpl.makeIntrinsic(mtype, lform, Intrinsic.IDENTITY); |
| if (ptype.isPrimitive()) { |
| try { |
| final MethodType mt = methodType(ptype, ptype); |
| return Lookup.PUBLIC_LOOKUP.findStatic(MethodHandles.class, "identity", mt); |
| } catch (NoSuchMethodException | IllegalAccessException e) { |
| throw new AssertionError(e); |
| } |
| } else { |
| return new Transformers.ReferenceIdentity(ptype); |
| } |
| } |
| |
| // Android-added: helper methods for identity(). |
| /** @hide */ public static byte identity(byte val) { return val; } |
| /** @hide */ public static boolean identity(boolean val) { return val; } |
| /** @hide */ public static char identity(char val) { return val; } |
| /** @hide */ public static short identity(short val) { return val; } |
| /** @hide */ public static int identity(int val) { return val; } |
| /** @hide */ public static long identity(long val) { return val; } |
| /** @hide */ public static float identity(float val) { return val; } |
| /** @hide */ public static double identity(double val) { return val; } |
| |
| private static MethodHandle zero(Wrapper btw, Class<?> rtype) { |
| int pos = btw.ordinal(); |
| MethodHandle zero = ZERO_MHS[pos]; |
| if (zero == null) { |
| zero = setCachedMethodHandle(ZERO_MHS, pos, makeZero(btw.primitiveType())); |
| } |
| if (zero.type().returnType() == rtype) |
| return zero; |
| assert(btw == Wrapper.OBJECT); |
| return makeZero(rtype); |
| } |
| private static final MethodHandle[] ZERO_MHS = new MethodHandle[Wrapper.COUNT]; |
| private static MethodHandle makeZero(Class<?> rtype) { |
| // Android-changed: use Android specific implementation. |
| // MethodType mtype = methodType(rtype); |
| // LambdaForm lform = LambdaForm.zeroForm(BasicType.basicType(rtype)); |
| // return MethodHandleImpl.makeIntrinsic(mtype, lform, Intrinsic.ZERO); |
| return new Transformers.ZeroValue(rtype); |
| } |
| |
| private static synchronized MethodHandle setCachedMethodHandle(MethodHandle[] cache, int pos, MethodHandle value) { |
| // Simulate a CAS, to avoid racy duplication of results. |
| MethodHandle prev = cache[pos]; |
| if (prev != null) return prev; |
| return cache[pos] = value; |
| } |
| |
| /** |
| * Provides a target method handle with one or more <em>bound arguments</em> |
| * in advance of the method handle's invocation. |
| * The formal parameters to the target corresponding to the bound |
| * arguments are called <em>bound parameters</em>. |
| * Returns a new method handle which saves away the bound arguments. |
| * When it is invoked, it receives arguments for any non-bound parameters, |
| * binds the saved arguments to their corresponding parameters, |
| * and calls the original target. |
| * <p> |
| * The type of the new method handle will drop the types for the bound |
| * parameters from the original target type, since the new method handle |
| * will no longer require those arguments to be supplied by its callers. |
| * <p> |
| * Each given argument object must match the corresponding bound parameter type. |
| * If a bound parameter type is a primitive, the argument object |
| * must be a wrapper, and will be unboxed to produce the primitive value. |
| * <p> |
| * The {@code pos} argument selects which parameters are to be bound. |
| * It may range between zero and <i>N-L</i> (inclusively), |
| * where <i>N</i> is the arity of the target method handle |
| * and <i>L</i> is the length of the values array. |
| * @param target the method handle to invoke after the argument is inserted |
| * @param pos where to insert the argument (zero for the first) |
| * @param values the series of arguments to insert |
| * @return a method handle which inserts an additional argument, |
| * before calling the original method handle |
| * @throws NullPointerException if the target or the {@code values} array is null |
| * @see MethodHandle#bindTo |
| */ |
| public static |
| MethodHandle insertArguments(MethodHandle target, int pos, Object... values) { |
| int insCount = values.length; |
| Class<?>[] ptypes = insertArgumentsChecks(target, insCount, pos); |
| if (insCount == 0) { |
| return target; |
| } |
| |
| // Throw ClassCastExceptions early if we can't cast any of the provided values |
| // to the required type. |
| for (int i = 0; i < insCount; i++) { |
| final Class<?> ptype = ptypes[pos + i]; |
| if (!ptype.isPrimitive()) { |
| ptypes[pos + i].cast(values[i]); |
| } else { |
| // Will throw a ClassCastException if something terrible happens. |
| values[i] = Wrapper.forPrimitiveType(ptype).convert(values[i], ptype); |
| } |
| } |
| |
| return new Transformers.InsertArguments(target, pos, values); |
| } |
| |
| // Android-changed: insertArgumentPrimitive is unused. |
| // |
| // private static BoundMethodHandle insertArgumentPrimitive(BoundMethodHandle result, int pos, |
| // Class<?> ptype, Object value) { |
| // Wrapper w = Wrapper.forPrimitiveType(ptype); |
| // // perform unboxing and/or primitive conversion |
| // value = w.convert(value, ptype); |
| // switch (w) { |
| // case INT: return result.bindArgumentI(pos, (int)value); |
| // case LONG: return result.bindArgumentJ(pos, (long)value); |
| // case FLOAT: return result.bindArgumentF(pos, (float)value); |
| // case DOUBLE: return result.bindArgumentD(pos, (double)value); |
| // default: return result.bindArgumentI(pos, ValueConversions.widenSubword(value)); |
| // } |
| // } |
| |
| private static Class<?>[] insertArgumentsChecks(MethodHandle target, int insCount, int pos) throws RuntimeException { |
| MethodType oldType = target.type(); |
| int outargs = oldType.parameterCount(); |
| int inargs = outargs - insCount; |
| if (inargs < 0) |
| throw newIllegalArgumentException("too many values to insert"); |
| if (pos < 0 || pos > inargs) |
| throw newIllegalArgumentException("no argument type to append"); |
| return oldType.ptypes(); |
| } |
| |
| // Android-changed: inclusive language preference for 'placeholder'. |
| /** |
| * Produces a method handle which will discard some placeholder arguments |
| * before calling some other specified <i>target</i> method handle. |
| * The type of the new method handle will be the same as the target's type, |
| * except it will also include the placeholder argument types, |
| * at some given position. |
| * <p> |
| * The {@code pos} argument may range between zero and <i>N</i>, |
| * where <i>N</i> is the arity of the target. |
| * If {@code pos} is zero, the placeholder arguments will precede |
| * the target's real arguments; if {@code pos} is <i>N</i> |
| * they will come after. |
| * <p> |
| * <b>Example:</b> |
| * <blockquote><pre>{@code |
| import static java.lang.invoke.MethodHandles.*; |
| import static java.lang.invoke.MethodType.*; |
| ... |
| MethodHandle cat = lookup().findVirtual(String.class, |
| "concat", methodType(String.class, String.class)); |
| assertEquals("xy", (String) cat.invokeExact("x", "y")); |
| MethodType bigType = cat.type().insertParameterTypes(0, int.class, String.class); |
| MethodHandle d0 = dropArguments(cat, 0, bigType.parameterList().subList(0,2)); |
| assertEquals(bigType, d0.type()); |
| assertEquals("yz", (String) d0.invokeExact(123, "x", "y", "z")); |
| * }</pre></blockquote> |
| * <p> |
| * This method is also equivalent to the following code: |
| * <blockquote><pre> |
| * {@link #dropArguments(MethodHandle,int,Class...) dropArguments}{@code (target, pos, valueTypes.toArray(new Class[0]))} |
| * </pre></blockquote> |
| * @param target the method handle to invoke after the arguments are dropped |
| * @param valueTypes the type(s) of the argument(s) to drop |
| * @param pos position of first argument to drop (zero for the leftmost) |
| * @return a method handle which drops arguments of the given types, |
| * before calling the original method handle |
| * @throws NullPointerException if the target is null, |
| * or if the {@code valueTypes} list or any of its elements is null |
| * @throws IllegalArgumentException if any element of {@code valueTypes} is {@code void.class}, |
| * or if {@code pos} is negative or greater than the arity of the target, |
| * or if the new method handle's type would have too many parameters |
| */ |
| public static |
| MethodHandle dropArguments(MethodHandle target, int pos, List<Class<?>> valueTypes) { |
| return dropArguments0(target, pos, copyTypes(valueTypes.toArray())); |
| } |
| |
| private static List<Class<?>> copyTypes(Object[] array) { |
| return Arrays.asList(Arrays.copyOf(array, array.length, Class[].class)); |
| } |
| |
| private static |
| MethodHandle dropArguments0(MethodHandle target, int pos, List<Class<?>> valueTypes) { |
| MethodType oldType = target.type(); // get NPE |
| int dropped = dropArgumentChecks(oldType, pos, valueTypes); |
| MethodType newType = oldType.insertParameterTypes(pos, valueTypes); |
| if (dropped == 0) return target; |
| // Android-changed: transformer implementation. |
| // BoundMethodHandle result = target.rebind(); |
| // LambdaForm lform = result.form; |
| // int insertFormArg = 1 + pos; |
| // for (Class<?> ptype : valueTypes) { |
| // lform = lform.editor().addArgumentForm(insertFormArg++, BasicType.basicType(ptype)); |
| // } |
| // result = result.copyWith(newType, lform); |
| // return result; |
| return new Transformers.DropArguments(newType, target, pos, dropped); |
| } |
| |
| private static int dropArgumentChecks(MethodType oldType, int pos, List<Class<?>> valueTypes) { |
| int dropped = valueTypes.size(); |
| MethodType.checkSlotCount(dropped); |
| int outargs = oldType.parameterCount(); |
| int inargs = outargs + dropped; |
| if (pos < 0 || pos > outargs) |
| throw newIllegalArgumentException("no argument type to remove" |
| + Arrays.asList(oldType, pos, valueTypes, inargs, outargs) |
| ); |
| return dropped; |
| } |
| |
| // Android-changed: inclusive language preference for 'placeholder'. |
| /** |
| * Produces a method handle which will discard some placeholder arguments |
| * before calling some other specified <i>target</i> method handle. |
| * The type of the new method handle will be the same as the target's type, |
| * except it will also include the placeholder argument types, |
| * at some given position. |
| * <p> |
| * The {@code pos} argument may range between zero and <i>N</i>, |
| * where <i>N</i> is the arity of the target. |
| * If {@code pos} is zero, the placeholder arguments will precede |
| * the target's real arguments; if {@code pos} is <i>N</i> |
| * they will come after. |
| * @apiNote |
| * <blockquote><pre>{@code |
| import static java.lang.invoke.MethodHandles.*; |
| import static java.lang.invoke.MethodType.*; |
| ... |
| MethodHandle cat = lookup().findVirtual(String.class, |
| "concat", methodType(String.class, String.class)); |
| assertEquals("xy", (String) cat.invokeExact("x", "y")); |
| MethodHandle d0 = dropArguments(cat, 0, String.class); |
| assertEquals("yz", (String) d0.invokeExact("x", "y", "z")); |
| MethodHandle d1 = dropArguments(cat, 1, String.class); |
| assertEquals("xz", (String) d1.invokeExact("x", "y", "z")); |
| MethodHandle d2 = dropArguments(cat, 2, String.class); |
| assertEquals("xy", (String) d2.invokeExact("x", "y", "z")); |
| MethodHandle d12 = dropArguments(cat, 1, int.class, boolean.class); |
| assertEquals("xz", (String) d12.invokeExact("x", 12, true, "z")); |
| * }</pre></blockquote> |
| * <p> |
| * This method is also equivalent to the following code: |
| * <blockquote><pre> |
| * {@link #dropArguments(MethodHandle,int,List) dropArguments}{@code (target, pos, Arrays.asList(valueTypes))} |
| * </pre></blockquote> |
| * @param target the method handle to invoke after the arguments are dropped |
| * @param valueTypes the type(s) of the argument(s) to drop |
| * @param pos position of first argument to drop (zero for the leftmost) |
| * @return a method handle which drops arguments of the given types, |
| * before calling the original method handle |
| * @throws NullPointerException if the target is null, |
| * or if the {@code valueTypes} array or any of its elements is null |
| * @throws IllegalArgumentException if any element of {@code valueTypes} is {@code void.class}, |
| * or if {@code pos} is negative or greater than the arity of the target, |
| * or if the new method handle's type would have |
| * <a href="MethodHandle.html#maxarity">too many parameters</a> |
| */ |
| public static |
| MethodHandle dropArguments(MethodHandle target, int pos, Class<?>... valueTypes) { |
| return dropArguments0(target, pos, copyTypes(valueTypes)); |
| } |
| |
| // private version which allows caller some freedom with error handling |
| private static MethodHandle dropArgumentsToMatch(MethodHandle target, int skip, List<Class<?>> newTypes, int pos, |
| boolean nullOnFailure) { |
| newTypes = copyTypes(newTypes.toArray()); |
| List<Class<?>> oldTypes = target.type().parameterList(); |
| int match = oldTypes.size(); |
| if (skip != 0) { |
| if (skip < 0 || skip > match) { |
| throw newIllegalArgumentException("illegal skip", skip, target); |
| } |
| oldTypes = oldTypes.subList(skip, match); |
| match -= skip; |
| } |
| List<Class<?>> addTypes = newTypes; |
| int add = addTypes.size(); |
| if (pos != 0) { |
| if (pos < 0 || pos > add) { |
| throw newIllegalArgumentException("illegal pos", pos, newTypes); |
| } |
| addTypes = addTypes.subList(pos, add); |
| add -= pos; |
| assert(addTypes.size() == add); |
| } |
| // Do not add types which already match the existing arguments. |
| if (match > add || !oldTypes.equals(addTypes.subList(0, match))) { |
| if (nullOnFailure) { |
| return null; |
| } |
| throw newIllegalArgumentException("argument lists do not match", oldTypes, newTypes); |
| } |
| addTypes = addTypes.subList(match, add); |
| add -= match; |
| assert(addTypes.size() == add); |
| // newTypes: ( P*[pos], M*[match], A*[add] ) |
| // target: ( S*[skip], M*[match] ) |
| MethodHandle adapter = target; |
| if (add > 0) { |
| adapter = dropArguments0(adapter, skip+ match, addTypes); |
| } |
| // adapter: (S*[skip], M*[match], A*[add] ) |
| if (pos > 0) { |
| adapter = dropArguments0(adapter, skip, newTypes.subList(0, pos)); |
| } |
| // adapter: (S*[skip], P*[pos], M*[match], A*[add] ) |
| return adapter; |
| } |
| |
| // Android-changed: inclusive language preference for 'placeholder'. |
| /** |
| * Adapts a target method handle to match the given parameter type list. If necessary, adds placeholder arguments. Some |
| * leading parameters can be skipped before matching begins. The remaining types in the {@code target}'s parameter |
| * type list must be a sub-list of the {@code newTypes} type list at the starting position {@code pos}. The |
| * resulting handle will have the target handle's parameter type list, with any non-matching parameter types (before |
| * or after the matching sub-list) inserted in corresponding positions of the target's original parameters, as if by |
| * {@link #dropArguments(MethodHandle, int, Class[])}. |
| * <p> |
| * The resulting handle will have the same return type as the target handle. |
| * <p> |
| * In more formal terms, assume these two type lists:<ul> |
| * <li>The target handle has the parameter type list {@code S..., M...}, with as many types in {@code S} as |
| * indicated by {@code skip}. The {@code M} types are those that are supposed to match part of the given type list, |
| * {@code newTypes}. |
| * <li>The {@code newTypes} list contains types {@code P..., M..., A...}, with as many types in {@code P} as |
| * indicated by {@code pos}. The {@code M} types are precisely those that the {@code M} types in the target handle's |
| * parameter type list are supposed to match. The types in {@code A} are additional types found after the matching |
| * sub-list. |
| * </ul> |
| * Given these assumptions, the result of an invocation of {@code dropArgumentsToMatch} will have the parameter type |
| * list {@code S..., P..., M..., A...}, with the {@code P} and {@code A} types inserted as if by |
| * {@link #dropArguments(MethodHandle, int, Class[])}. |
| * |
| * @apiNote |
| * Two method handles whose argument lists are "effectively identical" (i.e., identical in a common prefix) may be |
| * mutually converted to a common type by two calls to {@code dropArgumentsToMatch}, as follows: |
| * <blockquote><pre>{@code |
| import static java.lang.invoke.MethodHandles.*; |
| import static java.lang.invoke.MethodType.*; |
| ... |
| ... |
| MethodHandle h0 = constant(boolean.class, true); |
| MethodHandle h1 = lookup().findVirtual(String.class, "concat", methodType(String.class, String.class)); |
| MethodType bigType = h1.type().insertParameterTypes(1, String.class, int.class); |
| MethodHandle h2 = dropArguments(h1, 0, bigType.parameterList()); |
| if (h1.type().parameterCount() < h2.type().parameterCount()) |
| h1 = dropArgumentsToMatch(h1, 0, h2.type().parameterList(), 0); // lengthen h1 |
| else |
| h2 = dropArgumentsToMatch(h2, 0, h1.type().parameterList(), 0); // lengthen h2 |
| MethodHandle h3 = guardWithTest(h0, h1, h2); |
| assertEquals("xy", h3.invoke("x", "y", 1, "a", "b", "c")); |
| * }</pre></blockquote> |
| * @param target the method handle to adapt |
| * @param skip number of targets parameters to disregard (they will be unchanged) |
| * @param newTypes the list of types to match {@code target}'s parameter type list to |
| * @param pos place in {@code newTypes} where the non-skipped target parameters must occur |
| * @return a possibly adapted method handle |
| * @throws NullPointerException if either argument is null |
| * @throws IllegalArgumentException if any element of {@code newTypes} is {@code void.class}, |
| * or if {@code skip} is negative or greater than the arity of the target, |
| * or if {@code pos} is negative or greater than the newTypes list size, |
| * or if {@code newTypes} does not contain the {@code target}'s non-skipped parameter types at position |
| * {@code pos}. |
| * @since 9 |
| */ |
| public static |
| MethodHandle dropArgumentsToMatch(MethodHandle target, int skip, List<Class<?>> newTypes, int pos) { |
| Objects.requireNonNull(target); |
| Objects.requireNonNull(newTypes); |
| return dropArgumentsToMatch(target, skip, newTypes, pos, false); |
| } |
| |
| /** |
| * Drop the return value of the target handle (if any). |
| * The returned method handle will have a {@code void} return type. |
| * |
| * @param target the method handle to adapt |
| * @return a possibly adapted method handle |
| * @throws NullPointerException if {@code target} is null |
| * @since 16 |
| */ |
| public static MethodHandle dropReturn(MethodHandle target) { |
| Objects.requireNonNull(target); |
| MethodType oldType = target.type(); |
| Class<?> oldReturnType = oldType.returnType(); |
| if (oldReturnType == void.class) |
| return target; |
| |
| MethodType newType = oldType.changeReturnType(void.class); |
| // Android-changed: no support for BoundMethodHandle or LambdaForm. |
| // BoundMethodHandle result = target.rebind(); |
| // LambdaForm lform = result.editor().filterReturnForm(V_TYPE, true); |
| // result = result.copyWith(newType, lform); |
| // return result; |
| return target.asType(newType); |
| } |
| |
| /** |
| * Adapts a target method handle by pre-processing |
| * one or more of its arguments, each with its own unary filter function, |
| * and then calling the target with each pre-processed argument |
| * replaced by the result of its corresponding filter function. |
| * <p> |
| * The pre-processing is performed by one or more method handles, |
| * specified in the elements of the {@code filters} array. |
| * The first element of the filter array corresponds to the {@code pos} |
| * argument of the target, and so on in sequence. |
| * The filter functions are invoked in left to right order. |
| * <p> |
| * Null arguments in the array are treated as identity functions, |
| * and the corresponding arguments left unchanged. |
| * (If there are no non-null elements in the array, the original target is returned.) |
| * Each filter is applied to the corresponding argument of the adapter. |
| * <p> |
| * If a filter {@code F} applies to the {@code N}th argument of |
| * the target, then {@code F} must be a method handle which |
| * takes exactly one argument. The type of {@code F}'s sole argument |
| * replaces the corresponding argument type of the target |
| * in the resulting adapted method handle. |
| * The return type of {@code F} must be identical to the corresponding |
| * parameter type of the target. |
| * <p> |
| * It is an error if there are elements of {@code filters} |
| * (null or not) |
| * which do not correspond to argument positions in the target. |
| * <p><b>Example:</b> |
| * <blockquote><pre>{@code |
| import static java.lang.invoke.MethodHandles.*; |
| import static java.lang.invoke.MethodType.*; |
| ... |
| MethodHandle cat = lookup().findVirtual(String.class, |
| "concat", methodType(String.class, String.class)); |
| MethodHandle upcase = lookup().findVirtual(String.class, |
| "toUpperCase", methodType(String.class)); |
| assertEquals("xy", (String) cat.invokeExact("x", "y")); |
| MethodHandle f0 = filterArguments(cat, 0, upcase); |
| assertEquals("Xy", (String) f0.invokeExact("x", "y")); // Xy |
| MethodHandle f1 = filterArguments(cat, 1, upcase); |
| assertEquals("xY", (String) f1.invokeExact("x", "y")); // xY |
| MethodHandle f2 = filterArguments(cat, 0, upcase, upcase); |
| assertEquals("XY", (String) f2.invokeExact("x", "y")); // XY |
| * }</pre></blockquote> |
| * <p>Here is pseudocode for the resulting adapter. In the code, {@code T} |
| * denotes the return type of both the {@code target} and resulting adapter. |
| * {@code P}/{@code p} and {@code B}/{@code b} represent the types and values |
| * of the parameters and arguments that precede and follow the filter position |
| * {@code pos}, respectively. {@code A[i]}/{@code a[i]} stand for the types and |
| * values of the filtered parameters and arguments; they also represent the |
| * return types of the {@code filter[i]} handles. The latter accept arguments |
| * {@code v[i]} of type {@code V[i]}, which also appear in the signature of |
| * the resulting adapter. |
| * <blockquote><pre>{@code |
| * T target(P... p, A[i]... a[i], B... b); |
| * A[i] filter[i](V[i]); |
| * T adapter(P... p, V[i]... v[i], B... b) { |
| * return target(p..., filter[i](v[i])..., b...); |
| * } |
| * }</pre></blockquote> |
| * <p> |
| * <em>Note:</em> The resulting adapter is never a {@linkplain MethodHandle#asVarargsCollector |
| * variable-arity method handle}, even if the original target method handle was. |
| * |
| * @param target the method handle to invoke after arguments are filtered |
| * @param pos the position of the first argument to filter |
| * @param filters method handles to call initially on filtered arguments |
| * @return method handle which incorporates the specified argument filtering logic |
| * @throws NullPointerException if the target is null |
| * or if the {@code filters} array is null |
| * @throws IllegalArgumentException if a non-null element of {@code filters} |
| * does not match a corresponding argument type of target as described above, |
| * or if the {@code pos+filters.length} is greater than {@code target.type().parameterCount()}, |
| * or if the resulting method handle's type would have |
| * <a href="MethodHandle.html#maxarity">too many parameters</a> |
| */ |
| public static |
| MethodHandle filterArguments(MethodHandle target, int pos, MethodHandle... filters) { |
| filterArgumentsCheckArity(target, pos, filters); |
| MethodHandle adapter = target; |
| // Android-changed: transformer implementation. |
| // process filters in reverse order so that the invocation of |
| // the resulting adapter will invoke the filters in left-to-right order |
| // for (int i = filters.length - 1; i >= 0; --i) { |
| // MethodHandle filter = filters[i]; |
| // if (filter == null) continue; // ignore null elements of filters |
| // adapter = filterArgument(adapter, pos + i, filter); |
| // } |
| // return adapter; |
| for (int i = 0; i < filters.length; ++i) { |
| filterArgumentChecks(target, i + pos, filters[i]); |
| } |
| return new Transformers.FilterArguments(target, pos, filters); |
| } |
| |
| /*non-public*/ static |
| MethodHandle filterArgument(MethodHandle target, int pos, MethodHandle filter) { |
| filterArgumentChecks(target, pos, filter); |
| // Android-changed: use Transformer implementation. |
| // MethodType targetType = target.type(); |
| // MethodType filterType = filter.type(); |
| // BoundMethodHandle result = target.rebind(); |
| // Class<?> newParamType = filterType.parameterType(0); |
| // LambdaForm lform = result.editor().filterArgumentForm(1 + pos, BasicType.basicType(newParamType)); |
| // MethodType newType = targetType.changeParameterType(pos, newParamType); |
| // result = result.copyWithExtendL(newType, lform, filter); |
| // return result; |
| return new Transformers.FilterArguments(target, pos, filter); |
| } |
| |
| private static void filterArgumentsCheckArity(MethodHandle target, int pos, MethodHandle[] filters) { |
| MethodType targetType = target.type(); |
| int maxPos = targetType.parameterCount(); |
| if (pos + filters.length > maxPos) |
| throw newIllegalArgumentException("too many filters"); |
| } |
| |
| private static void filterArgumentChecks(MethodHandle target, int pos, MethodHandle filter) throws RuntimeException { |
| MethodType targetType = target.type(); |
| MethodType filterType = filter.type(); |
| if (filterType.parameterCount() != 1 |
| || filterType.returnType() != targetType.parameterType(pos)) |
| throw newIllegalArgumentException("target and filter types do not match", targetType, filterType); |
| } |
| |
| /** |
| * Adapts a target method handle by pre-processing |
| * a sub-sequence of its arguments with a filter (another method handle). |
| * The pre-processed arguments are replaced by the result (if any) of the |
| * filter function. |
| * The target is then called on the modified (usually shortened) argument list. |
| * <p> |
| * If the filter returns a value, the target must accept that value as |
| * its argument in position {@code pos}, preceded and/or followed by |
| * any arguments not passed to the filter. |
| * If the filter returns void, the target must accept all arguments |
| * not passed to the filter. |
| * No arguments are reordered, and a result returned from the filter |
| * replaces (in order) the whole subsequence of arguments originally |
| * passed to the adapter. |
| * <p> |
| * The argument types (if any) of the filter |
| * replace zero or one argument types of the target, at position {@code pos}, |
| * in the resulting adapted method handle. |
| * The return type of the filter (if any) must be identical to the |
| * argument type of the target at position {@code pos}, and that target argument |
| * is supplied by the return value of the filter. |
| * <p> |
| * In all cases, {@code pos} must be greater than or equal to zero, and |
| * {@code pos} must also be less than or equal to the target's arity. |
| * <p><b>Example:</b> |
| * <blockquote><pre>{@code |
| import static java.lang.invoke.MethodHandles.*; |
| import static java.lang.invoke.MethodType.*; |
| ... |
| MethodHandle deepToString = publicLookup() |
| .findStatic(Arrays.class, "deepToString", methodType(String.class, Object[].class)); |
| |
| MethodHandle ts1 = deepToString.asCollector(String[].class, 1); |
| assertEquals("[strange]", (String) ts1.invokeExact("strange")); |
| |
| MethodHandle ts2 = deepToString.asCollector(String[].class, 2); |
| assertEquals("[up, down]", (String) ts2.invokeExact("up", "down")); |
| |
| MethodHandle ts3 = deepToString.asCollector(String[].class, 3); |
| MethodHandle ts3_ts2 = collectArguments(ts3, 1, ts2); |
| assertEquals("[top, [up, down], strange]", |
| (String) ts3_ts2.invokeExact("top", "up", "down", "strange")); |
| |
| MethodHandle ts3_ts2_ts1 = collectArguments(ts3_ts2, 3, ts1); |
| assertEquals("[top, [up, down], [strange]]", |
| (String) ts3_ts2_ts1.invokeExact("top", "up", "down", "strange")); |
| |
| MethodHandle ts3_ts2_ts3 = collectArguments(ts3_ts2, 1, ts3); |
| assertEquals("[top, [[up, down, strange], charm], bottom]", |
| (String) ts3_ts2_ts3.invokeExact("top", "up", "down", "strange", "charm", "bottom")); |
| * }</pre></blockquote> |
| * <p> Here is pseudocode for the resulting adapter: |
| * <blockquote><pre>{@code |
| * T target(A...,V,C...); |
| * V filter(B...); |
| * T adapter(A... a,B... b,C... c) { |
| * V v = filter(b...); |
| * return target(a...,v,c...); |
| * } |
| * // and if the filter has no arguments: |
| * T target2(A...,V,C...); |
| * V filter2(); |
| * T adapter2(A... a,C... c) { |
| * V v = filter2(); |
| * return target2(a...,v,c...); |
| * } |
| * // and if the filter has a void return: |
| * T target3(A...,C...); |
| * void filter3(B...); |
| * void adapter3(A... a,B... b,C... c) { |
| * filter3(b...); |
| * return target3(a...,c...); |
| * } |
| * }</pre></blockquote> |
| * <p> |
| * A collection adapter {@code collectArguments(mh, 0, coll)} is equivalent to |
| * one which first "folds" the affected arguments, and then drops them, in separate |
| * steps as follows: |
| * <blockquote><pre>{@code |
| * mh = MethodHandles.dropArguments(mh, 1, coll.type().parameterList()); //step 2 |
| * mh = MethodHandles.foldArguments(mh, coll); //step 1 |
| * }</pre></blockquote> |
| * If the target method handle consumes no arguments besides than the result |
| * (if any) of the filter {@code coll}, then {@code collectArguments(mh, 0, coll)} |
| * is equivalent to {@code filterReturnValue(coll, mh)}. |
| * If the filter method handle {@code coll} consumes one argument and produces |
| * a non-void result, then {@code collectArguments(mh, N, coll)} |
| * is equivalent to {@code filterArguments(mh, N, coll)}. |
| * Other equivalences are possible but would require argument permutation. |
| * |
| * @param target the method handle to invoke after filtering the subsequence of arguments |
| * @param pos the position of the first adapter argument to pass to the filter, |
| * and/or the target argument which receives the result of the filter |
| * @param filter method handle to call on the subsequence of arguments |
| * @return method handle which incorporates the specified argument subsequence filtering logic |
| * @throws NullPointerException if either argument is null |
| * @throws IllegalArgumentException if the return type of {@code filter} |
| * is non-void and is not the same as the {@code pos} argument of the target, |
| * or if {@code pos} is not between 0 and the target's arity, inclusive, |
| * or if the resulting method handle's type would have |
| * <a href="MethodHandle.html#maxarity">too many parameters</a> |
| * @see MethodHandles#foldArguments |
| * @see MethodHandles#filterArguments |
| * @see MethodHandles#filterReturnValue |
| */ |
| public static |
| MethodHandle collectArguments(MethodHandle target, int pos, MethodHandle filter) { |
| MethodType newType = collectArgumentsChecks(target, pos, filter); |
| return new Transformers.CollectArguments(target, filter, pos, newType); |
| } |
| |
| private static MethodType collectArgumentsChecks(MethodHandle target, int pos, MethodHandle filter) throws RuntimeException { |
| MethodType targetType = target.type(); |
| MethodType filterType = filter.type(); |
| Class<?> rtype = filterType.returnType(); |
| List<Class<?>> filterArgs = filterType.parameterList(); |
| if (rtype == void.class) { |
| return targetType.insertParameterTypes(pos, filterArgs); |
| } |
| if (rtype != targetType.parameterType(pos)) { |
| throw newIllegalArgumentException("target and filter types do not match", targetType, filterType); |
| } |
| return targetType.dropParameterTypes(pos, pos+1).insertParameterTypes(pos, filterArgs); |
| } |
| |
| /** |
| * Adapts a target method handle by post-processing |
| * its return value (if any) with a filter (another method handle). |
| * The result of the filter is returned from the adapter. |
| * <p> |
| * If the target returns a value, the filter must accept that value as |
| * its only argument. |
| * If the target returns void, the filter must accept no arguments. |
| * <p> |
| * The return type of the filter |
| * replaces the return type of the target |
| * in the resulting adapted method handle. |
| * The argument type of the filter (if any) must be identical to the |
| * return type of the target. |
| * <p><b>Example:</b> |
| * <blockquote><pre>{@code |
| import static java.lang.invoke.MethodHandles.*; |
| import static java.lang.invoke.MethodType.*; |
| ... |
| MethodHandle cat = lookup().findVirtual(String.class, |
| "concat", methodType(String.class, String.class)); |
| MethodHandle length = lookup().findVirtual(String.class, |
| "length", methodType(int.class)); |
| System.out.println((String) cat.invokeExact("x", "y")); // xy |
| MethodHandle f0 = filterReturnValue(cat, length); |
| System.out.println((int) f0.invokeExact("x", "y")); // 2 |
| * }</pre></blockquote> |
| * <p>Here is pseudocode for the resulting adapter. In the code, |
| * {@code T}/{@code t} represent the result type and value of the |
| * {@code target}; {@code V}, the result type of the {@code filter}; and |
| * {@code A}/{@code a}, the types and values of the parameters and arguments |
| * of the {@code target} as well as the resulting adapter. |
| * <blockquote><pre>{@code |
| * T target(A...); |
| * V filter(T); |
| * V adapter(A... a) { |
| * T t = target(a...); |
| * return filter(t); |
| * } |
| * // and if the target has a void return: |
| * void target2(A...); |
| * V filter2(); |
| * V adapter2(A... a) { |
| * target2(a...); |
| * return filter2(); |
| * } |
| * // and if the filter has a void return: |
| * T target3(A...); |
| * void filter3(V); |
| * void adapter3(A... a) { |
| * T t = target3(a...); |
| * filter3(t); |
| * } |
| * }</pre></blockquote> |
| * <p> |
| * <em>Note:</em> The resulting adapter is never a {@linkplain MethodHandle#asVarargsCollector |
| * variable-arity method handle}, even if the original target method handle was. |
| * @param target the method handle to invoke before filtering the return value |
| * @param filter method handle to call on the return value |
| * @return method handle which incorporates the specified return value filtering logic |
| * @throws NullPointerException if either argument is null |
| * @throws IllegalArgumentException if the argument list of {@code filter} |
| * does not match the return type of target as described above |
| */ |
| public static |
| MethodHandle filterReturnValue(MethodHandle target, MethodHandle filter) { |
| MethodType targetType = target.type(); |
| MethodType filterType = filter.type(); |
| filterReturnValueChecks(targetType, filterType); |
| // Android-changed: use a transformer. |
| // BoundMethodHandle result = target.rebind(); |
| // BasicType rtype = BasicType.basicType(filterType.returnType()); |
| // LambdaForm lform = result.editor().filterReturnForm(rtype, false); |
| // MethodType newType = targetType.changeReturnType(filterType.returnType()); |
| // result = result.copyWithExtendL(newType, lform, filter); |
| // return result; |
| return new Transformers.FilterReturnValue(target, filter); |
| } |
| |
| private static void filterReturnValueChecks(MethodType targetType, MethodType filterType) throws RuntimeException { |
| Class<?> rtype = targetType.returnType(); |
| int filterValues = filterType.parameterCount(); |
| if (filterValues == 0 |
| ? (rtype != void.class) |
| : (rtype != filterType.parameterType(0) || filterValues != 1)) |
| throw newIllegalArgumentException("target and filter types do not match", targetType, filterType); |
| } |
| |
| /** |
| * Adapts a target method handle by pre-processing |
| * some of its arguments, and then calling the target with |
| * the result of the pre-processing, inserted into the original |
| * sequence of arguments. |
| * <p> |
| * The pre-processing is performed by {@code combiner}, a second method handle. |
| * Of the arguments passed to the adapter, the first {@code N} arguments |
| * are copied to the combiner, which is then called. |
| * (Here, {@code N} is defined as the parameter count of the combiner.) |
| * After this, control passes to the target, with any result |
| * from the combiner inserted before the original {@code N} incoming |
| * arguments. |
| * <p> |
| * If the combiner returns a value, the first parameter type of the target |
| * must be identical with the return type of the combiner, and the next |
| * {@code N} parameter types of the target must exactly match the parameters |
| * of the combiner. |
| * <p> |
| * If the combiner has a void return, no result will be inserted, |
| * and the first {@code N} parameter types of the target |
| * must exactly match the parameters of the combiner. |
| * <p> |
| * The resulting adapter is the same type as the target, except that the |
| * first parameter type is dropped, |
| * if it corresponds to the result of the combiner. |
| * <p> |
| * (Note that {@link #dropArguments(MethodHandle,int,List) dropArguments} can be used to remove any arguments |
| * that either the combiner or the target does not wish to receive. |
| * If some of the incoming arguments are destined only for the combiner, |
| * consider using {@link MethodHandle#asCollector asCollector} instead, since those |
| * arguments will not need to be live on the stack on entry to the |
| * target.) |
| * <p><b>Example:</b> |
| * <blockquote><pre>{@code |
| import static java.lang.invoke.MethodHandles.*; |
| import static java.lang.invoke.MethodType.*; |
| ... |
| MethodHandle trace = publicLookup().findVirtual(java.io.PrintStream.class, |
| "println", methodType(void.class, String.class)) |
| .bindTo(System.out); |
| MethodHandle cat = lookup().findVirtual(String.class, |
| "concat", methodType(String.class, String.class)); |
| assertEquals("boojum", (String) cat.invokeExact("boo", "jum")); |
| MethodHandle catTrace = foldArguments(cat, trace); |
| // also prints "boo": |
| assertEquals("boojum", (String) catTrace.invokeExact("boo", "jum")); |
| * }</pre></blockquote> |
| * <p>Here is pseudocode for the resulting adapter. In the code, {@code T} |
| * represents the result type of the {@code target} and resulting adapter. |
| * {@code V}/{@code v} represent the type and value of the parameter and argument |
| * of {@code target} that precedes the folding position; {@code V} also is |
| * the result type of the {@code combiner}. {@code A}/{@code a} denote the |
| * types and values of the {@code N} parameters and arguments at the folding |
| * position. {@code B}/{@code b} represent the types and values of the |
| * {@code target} parameters and arguments that follow the folded parameters |
| * and arguments. |
| * <blockquote><pre>{@code |
| * // there are N arguments in A... |
| * T target(V, A[N]..., B...); |
| * V combiner(A...); |
| * T adapter(A... a, B... b) { |
| * V v = combiner(a...); |
| * return target(v, a..., b...); |
| * } |
| * // and if the combiner has a void return: |
| * T target2(A[N]..., B...); |
| * void combiner2(A...); |
| * T adapter2(A... a, B... b) { |
| * combiner2(a...); |
| * return target2(a..., b...); |
| * } |
| * }</pre></blockquote> |
| * <p> |
| * <em>Note:</em> The resulting adapter is never a {@linkplain MethodHandle#asVarargsCollector |
| * variable-arity method handle}, even if the original target method handle was. |
| * @param target the method handle to invoke after arguments are combined |
| * @param combiner method handle to call initially on the incoming arguments |
| * @return method handle which incorporates the specified argument folding logic |
| * @throws NullPointerException if either argument is null |
| * @throws IllegalArgumentException if {@code combiner}'s return type |
| * is non-void and not the same as the first argument type of |
| * the target, or if the initial {@code N} argument types |
| * of the target |
| * (skipping one matching the {@code combiner}'s return type) |
| * are not identical with the argument types of {@code combiner} |
| */ |
| public static |
| MethodHandle foldArguments(MethodHandle target, MethodHandle combiner) { |
| return foldArguments(target, 0, combiner); |
| } |
| |
| /** |
| * Adapts a target method handle by pre-processing some of its arguments, starting at a given position, and then |
| * calling the target with the result of the pre-processing, inserted into the original sequence of arguments just |
| * before the folded arguments. |
| * <p> |
| * This method is closely related to {@link #foldArguments(MethodHandle, MethodHandle)}, but allows to control the |
| * position in the parameter list at which folding takes place. The argument controlling this, {@code pos}, is a |
| * zero-based index. The aforementioned method {@link #foldArguments(MethodHandle, MethodHandle)} assumes position |
| * 0. |
| * |
| * @apiNote Example: |
| * <blockquote><pre>{@code |
| import static java.lang.invoke.MethodHandles.*; |
| import static java.lang.invoke.MethodType.*; |
| ... |
| MethodHandle trace = publicLookup().findVirtual(java.io.PrintStream.class, |
| "println", methodType(void.class, String.class)) |
| .bindTo(System.out); |
| MethodHandle cat = lookup().findVirtual(String.class, |
| "concat", methodType(String.class, String.class)); |
| assertEquals("boojum", (String) cat.invokeExact("boo", "jum")); |
| MethodHandle catTrace = foldArguments(cat, 1, trace); |
| // also prints "jum": |
| assertEquals("boojum", (String) catTrace.invokeExact("boo", "jum")); |
| * }</pre></blockquote> |
| * <p>Here is pseudocode for the resulting adapter. In the code, {@code T} |
| * represents the result type of the {@code target} and resulting adapter. |
| * {@code V}/{@code v} represent the type and value of the parameter and argument |
| * of {@code target} that precedes the folding position; {@code V} also is |
| * the result type of the {@code combiner}. {@code A}/{@code a} denote the |
| * types and values of the {@code N} parameters and arguments at the folding |
| * position. {@code Z}/{@code z} and {@code B}/{@code b} represent the types |
| * and values of the {@code target} parameters and arguments that precede and |
| * follow the folded parameters and arguments starting at {@code pos}, |
| * respectively. |
| * <blockquote><pre>{@code |
| * // there are N arguments in A... |
| * T target(Z..., V, A[N]..., B...); |
| * V combiner(A...); |
| * T adapter(Z... z, A... a, B... b) { |
| * V v = combiner(a...); |
| * return target(z..., v, a..., b...); |
| * } |
| * // and if the combiner has a void return: |
| * T target2(Z..., A[N]..., B...); |
| * void combiner2(A...); |
| * T adapter2(Z... z, A... a, B... b) { |
| * combiner2(a...); |
| * return target2(z..., a..., b...); |
| * } |
| * }</pre></blockquote> |
| * <p> |
| * <em>Note:</em> The resulting adapter is never a {@linkplain MethodHandle#asVarargsCollector |
| * variable-arity method handle}, even if the original target method handle was. |
| * |
| * @param target the method handle to invoke after arguments are combined |
| * @param pos the position at which to start folding and at which to insert the folding result; if this is {@code |
| * 0}, the effect is the same as for {@link #foldArguments(MethodHandle, MethodHandle)}. |
| * @param combiner method handle to call initially on the incoming arguments |
| * @return method handle which incorporates the specified argument folding logic |
| * @throws NullPointerException if either argument is null |
| * @throws IllegalArgumentException if either of the following two conditions holds: |
| * (1) {@code combiner}'s return type is non-{@code void} and not the same as the argument type at position |
| * {@code pos} of the target signature; |
| * (2) the {@code N} argument types at position {@code pos} of the target signature (skipping one matching |
| * the {@code combiner}'s return type) are not identical with the argument types of {@code combiner}. |
| * |
| * @see #foldArguments(MethodHandle, MethodHandle) |
| * @since 9 |
| */ |
| public static |
| MethodHandle foldArguments(MethodHandle target, int pos, MethodHandle combiner) { |
| MethodType targetType = target.type(); |
| MethodType combinerType = combiner.type(); |
| Class<?> rtype = foldArgumentChecks(pos, targetType, combinerType); |
| // Android-changed: // Android-changed: transformer implementation. |
| // BoundMethodHandle result = target.rebind(); |
| // boolean dropResult = rtype == void.class; |
| // LambdaForm lform = result.editor().foldArgumentsForm(1 + pos, dropResult, combinerType.basicType()); |
| // MethodType newType = targetType; |
| // if (!dropResult) { |
| // newType = newType.dropParameterTypes(pos, pos + 1); |
| // } |
| // result = result.copyWithExtendL(newType, lform, combiner); |
| // return result; |
| |
| return new Transformers.FoldArguments(target, pos, combiner); |
| } |
| |
| private static Class<?> foldArgumentChecks(int foldPos, MethodType targetType, MethodType combinerType) { |
| int foldArgs = combinerType.parameterCount(); |
| Class<?> rtype = combinerType.returnType(); |
| int foldVals = rtype == void.class ? 0 : 1; |
| int afterInsertPos = foldPos + foldVals; |
| boolean ok = (targetType.parameterCount() >= afterInsertPos + foldArgs); |
| if (ok) { |
| for (int i = 0; i < foldArgs; i++) { |
| if (combinerType.parameterType(i) != targetType.parameterType(i + afterInsertPos)) { |
| ok = false; |
| break; |
| } |
| } |
| } |
| if (ok && foldVals != 0 && combinerType.returnType() != targetType.parameterType(foldPos)) |
| ok = false; |
| if (!ok) |
| throw misMatchedTypes("target and combiner types", targetType, combinerType); |
| return rtype; |
| } |
| |
| /** |
| * Makes a method handle which adapts a target method handle, |
| * by guarding it with a test, a boolean-valued method handle. |
| * If the guard fails, a fallback handle is called instead. |
| * All three method handles must have the same corresponding |
| * argument and return types, except that the return type |
| * of the test must be boolean, and the test is allowed |
| * to have fewer arguments than the other two method handles. |
| * <p> Here is pseudocode for the resulting adapter: |
| * <blockquote><pre>{@code |
| * boolean test(A...); |
| * T target(A...,B...); |
| * T fallback(A...,B...); |
| * T adapter(A... a,B... b) { |
| * if (test(a...)) |
| * return target(a..., b...); |
| * else |
| * return fallback(a..., b...); |
| * } |
| * }</pre></blockquote> |
| * Note that the test arguments ({@code a...} in the pseudocode) cannot |
| * be modified by execution of the test, and so are passed unchanged |
| * from the caller to the target or fallback as appropriate. |
| * @param test method handle used for test, must return boolean |
| * @param target method handle to call if test passes |
| * @param fallback method handle to call if test fails |
| * @return method handle which incorporates the specified if/then/else logic |
| * @throws NullPointerException if any argument is null |
| * @throws IllegalArgumentException if {@code test} does not return boolean, |
| * or if all three method types do not match (with the return |
| * type of {@code test} changed to match that of the target). |
| */ |
| public static |
| MethodHandle guardWithTest(MethodHandle test, |
| MethodHandle target, |
| MethodHandle fallback) { |
| MethodType gtype = test.type(); |
| MethodType ttype = target.type(); |
| MethodType ftype = fallback.type(); |
| if (!ttype.equals(ftype)) |
| throw misMatchedTypes("target and fallback types", ttype, ftype); |
| if (gtype.returnType() != boolean.class) |
| throw newIllegalArgumentException("guard type is not a predicate "+gtype); |
| List<Class<?>> targs = ttype.parameterList(); |
| List<Class<?>> gargs = gtype.parameterList(); |
| if (!targs.equals(gargs)) { |
| int gpc = gargs.size(), tpc = targs.size(); |
| if (gpc >= tpc || !targs.subList(0, gpc).equals(gargs)) |
| throw misMatchedTypes("target and test types", ttype, gtype); |
| test = dropArguments(test, gpc, targs.subList(gpc, tpc)); |
| gtype = test.type(); |
| } |
| |
| return new Transformers.GuardWithTest(test, target, fallback); |
| } |
| |
| static <T> RuntimeException misMatchedTypes(String what, T t1, T t2) { |
| return newIllegalArgumentException(what + " must match: " + t1 + " != " + t2); |
| } |
| |
| /** |
| * Makes a method handle which adapts a target method handle, |
| * by running it inside an exception handler. |
| * If the target returns normally, the adapter returns that value. |
| * If an exception matching the specified type is thrown, the fallback |
| * handle is called instead on the exception, plus the original arguments. |
| * <p> |
| * The target and handler must have the same corresponding |
| * argument and return types, except that handler may omit trailing arguments |
| * (similarly to the predicate in {@link #guardWithTest guardWithTest}). |
| * Also, the handler must have an extra leading parameter of {@code exType} or a supertype. |
| * <p> |
| * Here is pseudocode for the resulting adapter. In the code, {@code T} |
| * represents the return type of the {@code target} and {@code handler}, |
| * and correspondingly that of the resulting adapter; {@code A}/{@code a}, |
| * the types and values of arguments to the resulting handle consumed by |
| * {@code handler}; and {@code B}/{@code b}, those of arguments to the |
| * resulting handle discarded by {@code handler}. |
| * <blockquote><pre>{@code |
| * T target(A..., B...); |
| * T handler(ExType, A...); |
| * T adapter(A... a, B... b) { |
| * try { |
| * return target(a..., b...); |
| * } catch (ExType ex) { |
| * return handler(ex, a...); |
| * } |
| * } |
| * }</pre></blockquote> |
| * Note that the saved arguments ({@code a...} in the pseudocode) cannot |
| * be modified by execution of the target, and so are passed unchanged |
| * from the caller to the handler, if the handler is invoked. |
| * <p> |
| * The target and handler must return the same type, even if the handler |
| * always throws. (This might happen, for instance, because the handler |
| * is simulating a {@code finally} clause). |
| * To create such a throwing handler, compose the handler creation logic |
| * with {@link #throwException throwException}, |
| * in order to create a method handle of the correct return type. |
| * @param target method handle to call |
| * @param exType the type of exception which the handler will catch |
| * @param handler method handle to call if a matching exception is thrown |
| * @return method handle which incorporates the specified try/catch logic |
| * @throws NullPointerException if any argument is null |
| * @throws IllegalArgumentException if {@code handler} does not accept |
| * the given exception type, or if the method handle types do |
| * not match in their return types and their |
| * corresponding parameters |
| * @see MethodHandles#tryFinally(MethodHandle, MethodHandle) |
| */ |
| public static |
| MethodHandle catchException(MethodHandle target, |
| Class<? extends Throwable> exType, |
| MethodHandle handler) { |
| MethodType ttype = target.type(); |
| MethodType htype = handler.type(); |
| if (!Throwable.class.isAssignableFrom(exType)) |
| throw new ClassCastException(exType.getName()); |
| if (htype.parameterCount() < 1 || |
| !htype.parameterType(0).isAssignableFrom(exType)) |
| throw newIllegalArgumentException("handler does not accept exception type "+exType); |
| if (htype.returnType() != ttype.returnType()) |
| throw misMatchedTypes("target and handler return types", ttype, htype); |
| handler = dropArgumentsToMatch(handler, 1, ttype.parameterList(), 0, true); |
| if (handler == null) { |
| throw misMatchedTypes("target and handler types", ttype, htype); |
| } |
| // Android-changed: use Transformer implementation. |
| // return MethodHandleImpl.makeGuardWithCatch(target, exType, handler); |
| return new Transformers.CatchException(target, handler, exType); |
| } |
| |
| /** |
| * Produces a method handle which will throw exceptions of the given {@code exType}. |
| * The method handle will accept a single argument of {@code exType}, |
| * and immediately throw it as an exception. |
| * The method type will nominally specify a return of {@code returnType}. |
| * The return type may be anything convenient: It doesn't matter to the |
| * method handle's behavior, since it will never return normally. |
| * @param returnType the return type of the desired method handle |
| * @param exType the parameter type of the desired method handle |
| * @return method handle which can throw the given exceptions |
| * @throws NullPointerException if either argument is null |
| */ |
| public static |
| MethodHandle throwException(Class<?> returnType, Class<? extends Throwable> exType) { |
| if (!Throwable.class.isAssignableFrom(exType)) |
| throw new ClassCastException(exType.getName()); |
| // Android-changed: use Transformer implementation. |
| // return MethodHandleImpl.throwException(methodType(returnType, exType)); |
| return new Transformers.AlwaysThrow(returnType, exType); |
| } |
| |
| /** |
| * Constructs a method handle representing a loop with several loop variables that are updated and checked upon each |
| * iteration. Upon termination of the loop due to one of the predicates, a corresponding finalizer is run and |
| * delivers the loop's result, which is the return value of the resulting handle. |
| * <p> |
| * Intuitively, every loop is formed by one or more "clauses", each specifying a local <em>iteration variable</em> and/or a loop |
| * exit. Each iteration of the loop executes each clause in order. A clause can optionally update its iteration |
| * variable; it can also optionally perform a test and conditional loop exit. In order to express this logic in |
| * terms of method handles, each clause will specify up to four independent actions:<ul> |
| * <li><em>init:</em> Before the loop executes, the initialization of an iteration variable {@code v} of type {@code V}. |
| * <li><em>step:</em> When a clause executes, an update step for the iteration variable {@code v}. |
| * <li><em>pred:</em> When a clause executes, a predicate execution to test for loop exit. |
| * <li><em>fini:</em> If a clause causes a loop exit, a finalizer execution to compute the loop's return value. |
| * </ul> |
| * The full sequence of all iteration variable types, in clause order, will be notated as {@code (V...)}. |
| * The values themselves will be {@code (v...)}. When we speak of "parameter lists", we will usually |
| * be referring to types, but in some contexts (describing execution) the lists will be of actual values. |
| * <p> |
| * Some of these clause parts may be omitted according to certain rules, and useful default behavior is provided in |
| * this case. See below for a detailed description. |
| * <p> |
| * <em>Parameters optional everywhere:</em> |
| * Each clause function is allowed but not required to accept a parameter for each iteration variable {@code v}. |
| * As an exception, the init functions cannot take any {@code v} parameters, |
| * because those values are not yet computed when the init functions are executed. |
| * Any clause function may neglect to take any trailing subsequence of parameters it is entitled to take. |
| * In fact, any clause function may take no arguments at all. |
| * <p> |
| * <em>Loop parameters:</em> |
| * A clause function may take all the iteration variable values it is entitled to, in which case |
| * it may also take more trailing parameters. Such extra values are called <em>loop parameters</em>, |
| * with their types and values notated as {@code (A...)} and {@code (a...)}. |
| * These become the parameters of the resulting loop handle, to be supplied whenever the loop is executed. |
| * (Since init functions do not accept iteration variables {@code v}, any parameter to an |
| * init function is automatically a loop parameter {@code a}.) |
| * As with iteration variables, clause functions are allowed but not required to accept loop parameters. |
| * These loop parameters act as loop-invariant values visible across the whole loop. |
| * <p> |
| * <em>Parameters visible everywhere:</em> |
| * Each non-init clause function is permitted to observe the entire loop state, because it can be passed the full |
| * list {@code (v... a...)} of current iteration variable values and incoming loop parameters. |
| * The init functions can observe initial pre-loop state, in the form {@code (a...)}. |
| * Most clause functions will not need all of this information, but they will be formally connected to it |
| * as if by {@link #dropArguments}. |
| * <a id="astar"></a> |
| * More specifically, we shall use the notation {@code (V*)} to express an arbitrary prefix of a full |
| * sequence {@code (V...)} (and likewise for {@code (v*)}, {@code (A*)}, {@code (a*)}). |
| * In that notation, the general form of an init function parameter list |
| * is {@code (A*)}, and the general form of a non-init function parameter list is {@code (V*)} or {@code (V... A*)}. |
| * <p> |
| * <em>Checking clause structure:</em> |
| * Given a set of clauses, there is a number of checks and adjustments performed to connect all the parts of the |
| * loop. They are spelled out in detail in the steps below. In these steps, every occurrence of the word "must" |
| * corresponds to a place where {@link IllegalArgumentException} will be thrown if the required constraint is not |
| * met by the inputs to the loop combinator. |
| * <p> |
| * <em>Effectively identical sequences:</em> |
| * <a id="effid"></a> |
| * A parameter list {@code A} is defined to be <em>effectively identical</em> to another parameter list {@code B} |
| * if {@code A} and {@code B} are identical, or if {@code A} is shorter and is identical with a proper prefix of {@code B}. |
| * When speaking of an unordered set of parameter lists, we say they the set is "effectively identical" |
| * as a whole if the set contains a longest list, and all members of the set are effectively identical to |
| * that longest list. |
| * For example, any set of type sequences of the form {@code (V*)} is effectively identical, |
| * and the same is true if more sequences of the form {@code (V... A*)} are added. |
| * <p> |
| * <em>Step 0: Determine clause structure.</em><ol type="a"> |
| * <li>The clause array (of type {@code MethodHandle[][]}) must be non-{@code null} and contain at least one element. |
| * <li>The clause array may not contain {@code null}s or sub-arrays longer than four elements. |
| * <li>Clauses shorter than four elements are treated as if they were padded by {@code null} elements to length |
| * four. Padding takes place by appending elements to the array. |
| * <li>Clauses with all {@code null}s are disregarded. |
| * <li>Each clause is treated as a four-tuple of functions, called "init", "step", "pred", and "fini". |
| * </ol> |
| * <p> |
| * <em>Step 1A: Determine iteration variable types {@code (V...)}.</em><ol type="a"> |
| * <li>The iteration variable type for each clause is determined using the clause's init and step return types. |
| * <li>If both functions are omitted, there is no iteration variable for the corresponding clause ({@code void} is |
| * used as the type to indicate that). If one of them is omitted, the other's return type defines the clause's |
| * iteration variable type. If both are given, the common return type (they must be identical) defines the clause's |
| * iteration variable type. |
| * <li>Form the list of return types (in clause order), omitting all occurrences of {@code void}. |
| * <li>This list of types is called the "iteration variable types" ({@code (V...)}). |
| * </ol> |
| * <p> |
| * <em>Step 1B: Determine loop parameters {@code (A...)}.</em><ul> |
| * <li>Examine and collect init function parameter lists (which are of the form {@code (A*)}). |
| * <li>Examine and collect the suffixes of the step, pred, and fini parameter lists, after removing the iteration variable types. |
| * (They must have the form {@code (V... A*)}; collect the {@code (A*)} parts only.) |
| * <li>Do not collect suffixes from step, pred, and fini parameter lists that do not begin with all the iteration variable types. |
| * (These types will be checked in step 2, along with all the clause function types.) |
| * <li>Omitted clause functions are ignored. (Equivalently, they are deemed to have empty parameter lists.) |
| * <li>All of the collected parameter lists must be effectively identical. |
| * <li>The longest parameter list (which is necessarily unique) is called the "external parameter list" ({@code (A...)}). |
| * <li>If there is no such parameter list, the external parameter list is taken to be the empty sequence. |
| * <li>The combined list consisting of iteration variable types followed by the external parameter types is called |
| * the "internal parameter list". |
| * </ul> |
| * <p> |
| * <em>Step 1C: Determine loop return type.</em><ol type="a"> |
| * <li>Examine fini function return types, disregarding omitted fini functions. |
| * <li>If there are no fini functions, the loop return type is {@code void}. |
| * <li>Otherwise, the common return type {@code R} of the fini functions (their return types must be identical) defines the loop return |
| * type. |
| * </ol> |
| * <p> |
| * <em>Step 1D: Check other types.</em><ol type="a"> |
| * <li>There must be at least one non-omitted pred function. |
| * <li>Every non-omitted pred function must have a {@code boolean} return type. |
| * </ol> |
| * <p> |
| * <em>Step 2: Determine parameter lists.</em><ol type="a"> |
| * <li>The parameter list for the resulting loop handle will be the external parameter list {@code (A...)}. |
| * <li>The parameter list for init functions will be adjusted to the external parameter list. |
| * (Note that their parameter lists are already effectively identical to this list.) |
| * <li>The parameter list for every non-omitted, non-init (step, pred, and fini) function must be |
| * effectively identical to the internal parameter list {@code (V... A...)}. |
| * </ol> |
| * <p> |
| * <em>Step 3: Fill in omitted functions.</em><ol type="a"> |
| * <li>If an init function is omitted, use a {@linkplain #empty default value} for the clause's iteration variable |
| * type. |
| * <li>If a step function is omitted, use an {@linkplain #identity identity function} of the clause's iteration |
| * variable type; insert dropped argument parameters before the identity function parameter for the non-{@code void} |
| * iteration variables of preceding clauses. (This will turn the loop variable into a local loop invariant.) |
| * <li>If a pred function is omitted, use a constant {@code true} function. (This will keep the loop going, as far |
| * as this clause is concerned. Note that in such cases the corresponding fini function is unreachable.) |
| * <li>If a fini function is omitted, use a {@linkplain #empty default value} for the |
| * loop return type. |
| * </ol> |
| * <p> |
| * <em>Step 4: Fill in missing parameter types.</em><ol type="a"> |
| * <li>At this point, every init function parameter list is effectively identical to the external parameter list {@code (A...)}, |
| * but some lists may be shorter. For every init function with a short parameter list, pad out the end of the list. |
| * <li>At this point, every non-init function parameter list is effectively identical to the internal parameter |
| * list {@code (V... A...)}, but some lists may be shorter. For every non-init function with a short parameter list, |
| * pad out the end of the list. |
| * <li>Argument lists are padded out by {@linkplain #dropArgumentsToMatch(MethodHandle, int, List, int) dropping unused trailing arguments}. |
| * </ol> |
| * <p> |
| * <em>Final observations.</em><ol type="a"> |
| * <li>After these steps, all clauses have been adjusted by supplying omitted functions and arguments. |
| * <li>All init functions have a common parameter type list {@code (A...)}, which the final loop handle will also have. |
| * <li>All fini functions have a common return type {@code R}, which the final loop handle will also have. |
| * <li>All non-init functions have a common parameter type list {@code (V... A...)}, of |
| * (non-{@code void}) iteration variables {@code V} followed by loop parameters. |
| * <li>Each pair of init and step functions agrees in their return type {@code V}. |
| * <li>Each non-init function will be able to observe the current values {@code (v...)} of all iteration variables. |
| * <li>Every function will be able to observe the incoming values {@code (a...)} of all loop parameters. |
| * </ol> |
| * <p> |
| * <em>Example.</em> As a consequence of step 1A above, the {@code loop} combinator has the following property: |
| * <ul> |
| * <li>Given {@code N} clauses {@code Cn = {null, Sn, Pn}} with {@code n = 1..N}. |
| * <li>Suppose predicate handles {@code Pn} are either {@code null} or have no parameters. |
| * (Only one {@code Pn} has to be non-{@code null}.) |
| * <li>Suppose step handles {@code Sn} have signatures {@code (B1..BX)Rn}, for some constant {@code X>=N}. |
| * <li>Suppose {@code Q} is the count of non-void types {@code Rn}, and {@code (V1...VQ)} is the sequence of those types. |
| * <li>It must be that {@code Vn == Bn} for {@code n = 1..min(X,Q)}. |
| * <li>The parameter types {@code Vn} will be interpreted as loop-local state elements {@code (V...)}. |
| * <li>Any remaining types {@code BQ+1..BX} (if {@code Q<X}) will determine |
| * the resulting loop handle's parameter types {@code (A...)}. |
| * </ul> |
| * In this example, the loop handle parameters {@code (A...)} were derived from the step functions, |
| * which is natural if most of the loop computation happens in the steps. For some loops, |
| * the burden of computation might be heaviest in the pred functions, and so the pred functions |
| * might need to accept the loop parameter values. For loops with complex exit logic, the fini |
| * functions might need to accept loop parameters, and likewise for loops with complex entry logic, |
| * where the init functions will need the extra parameters. For such reasons, the rules for |
| * determining these parameters are as symmetric as possible, across all clause parts. |
| * In general, the loop parameters function as common invariant values across the whole |
| * loop, while the iteration variables function as common variant values, or (if there is |
| * no step function) as internal loop invariant temporaries. |
| * <p> |
| * <em>Loop execution.</em><ol type="a"> |
| * <li>When the loop is called, the loop input values are saved in locals, to be passed to |
| * every clause function. These locals are loop invariant. |
| * <li>Each init function is executed in clause order (passing the external arguments {@code (a...)}) |
| * and the non-{@code void} values are saved (as the iteration variables {@code (v...)}) into locals. |
| * These locals will be loop varying (unless their steps behave as identity functions, as noted above). |
| * <li>All function executions (except init functions) will be passed the internal parameter list, consisting of |
| * the non-{@code void} iteration values {@code (v...)} (in clause order) and then the loop inputs {@code (a...)} |
| * (in argument order). |
| * <li>The step and pred functions are then executed, in clause order (step before pred), until a pred function |
| * returns {@code false}. |
| * <li>The non-{@code void} result from a step function call is used to update the corresponding value in the |
| * sequence {@code (v...)} of loop variables. |
| * The updated value is immediately visible to all subsequent function calls. |
| * <li>If a pred function returns {@code false}, the corresponding fini function is called, and the resulting value |
| * (of type {@code R}) is returned from the loop as a whole. |
| * <li>If all the pred functions always return true, no fini function is ever invoked, and the loop cannot exit |
| * except by throwing an exception. |
| * </ol> |
| * <p> |
| * <em>Usage tips.</em> |
| * <ul> |
| * <li>Although each step function will receive the current values of <em>all</em> the loop variables, |
| * sometimes a step function only needs to observe the current value of its own variable. |
| * In that case, the step function may need to explicitly {@linkplain #dropArguments drop all preceding loop variables}. |
| * This will require mentioning their types, in an expression like {@code dropArguments(step, 0, V0.class, ...)}. |
| * <li>Loop variables are not required to vary; they can be loop invariant. A clause can create |
| * a loop invariant by a suitable init function with no step, pred, or fini function. This may be |
| * useful to "wire" an incoming loop argument into the step or pred function of an adjacent loop variable. |
| * <li>If some of the clause functions are virtual methods on an instance, the instance |
| * itself can be conveniently placed in an initial invariant loop "variable", using an initial clause |
| * like {@code new MethodHandle[]{identity(ObjType.class)}}. In that case, the instance reference |
| * will be the first iteration variable value, and it will be easy to use virtual |
| * methods as clause parts, since all of them will take a leading instance reference matching that value. |
| * </ul> |
| * <p> |
| * Here is pseudocode for the resulting loop handle. As above, {@code V} and {@code v} represent the types |
| * and values of loop variables; {@code A} and {@code a} represent arguments passed to the whole loop; |
| * and {@code R} is the common result type of all finalizers as well as of the resulting loop. |
| * <blockquote><pre>{@code |
| * V... init...(A...); |
| * boolean pred...(V..., A...); |
| * V... step...(V..., A...); |
| * R fini...(V..., A...); |
| * R loop(A... a) { |
| * V... v... = init...(a...); |
| * for (;;) { |
| * for ((v, p, s, f) in (v..., pred..., step..., fini...)) { |
| * v = s(v..., a...); |
| * if (!p(v..., a...)) { |
| * return f(v..., a...); |
| * } |
| * } |
| * } |
| * } |
| * }</pre></blockquote> |
| * Note that the parameter type lists {@code (V...)} and {@code (A...)} have been expanded |
| * to their full length, even though individual clause functions may neglect to take them all. |
| * As noted above, missing parameters are filled in as if by {@link #dropArgumentsToMatch(MethodHandle, int, List, int)}. |
| * |
| * @apiNote Example: |
| * <blockquote><pre>{@code |
| * // iterative implementation of the factorial function as a loop handle |
| * static int one(int k) { return 1; } |
| * static int inc(int i, int acc, int k) { return i + 1; } |
| * static int mult(int i, int acc, int k) { return i * acc; } |
| * static boolean pred(int i, int acc, int k) { return i < k; } |
| * static int fin(int i, int acc, int k) { return acc; } |
| * // assume MH_one, MH_inc, MH_mult, MH_pred, and MH_fin are handles to the above methods |
| * // null initializer for counter, should initialize to 0 |
| * MethodHandle[] counterClause = new MethodHandle[]{null, MH_inc}; |
| * MethodHandle[] accumulatorClause = new MethodHandle[]{MH_one, MH_mult, MH_pred, MH_fin}; |
| * MethodHandle loop = MethodHandles.loop(counterClause, accumulatorClause); |
| * assertEquals(120, loop.invoke(5)); |
| * }</pre></blockquote> |
| * The same example, dropping arguments and using combinators: |
| * <blockquote><pre>{@code |
| * // simplified implementation of the factorial function as a loop handle |
| * static int inc(int i) { return i + 1; } // drop acc, k |
| * static int mult(int i, int acc) { return i * acc; } //drop k |
| * static boolean cmp(int i, int k) { return i < k; } |
| * // assume MH_inc, MH_mult, and MH_cmp are handles to the above methods |
| * // null initializer for counter, should initialize to 0 |
| * MethodHandle MH_one = MethodHandles.constant(int.class, 1); |
| * MethodHandle MH_pred = MethodHandles.dropArguments(MH_cmp, 1, int.class); // drop acc |
| * MethodHandle MH_fin = MethodHandles.dropArguments(MethodHandles.identity(int.class), 0, int.class); // drop i |
| * MethodHandle[] counterClause = new MethodHandle[]{null, MH_inc}; |
| * MethodHandle[] accumulatorClause = new MethodHandle[]{MH_one, MH_mult, MH_pred, MH_fin}; |
| * MethodHandle loop = MethodHandles.loop(counterClause, accumulatorClause); |
| * assertEquals(720, loop.invoke(6)); |
| * }</pre></blockquote> |
| * A similar example, using a helper object to hold a loop parameter: |
| * <blockquote><pre>{@code |
| * // instance-based implementation of the factorial function as a loop handle |
| * static class FacLoop { |
| * final int k; |
| * FacLoop(int k) { this.k = k; } |
| * int inc(int i) { return i + 1; } |
| * int mult(int i, int acc) { return i * acc; } |
| * boolean pred(int i) { return i < k; } |
| * int fin(int i, int acc) { return acc; } |
| * } |
| * // assume MH_FacLoop is a handle to the constructor |
| * // assume MH_inc, MH_mult, MH_pred, and MH_fin are handles to the above methods |
| * // null initializer for counter, should initialize to 0 |
| * MethodHandle MH_one = MethodHandles.constant(int.class, 1); |
| * MethodHandle[] instanceClause = new MethodHandle[]{MH_FacLoop}; |
| * MethodHandle[] counterClause = new MethodHandle[]{null, MH_inc}; |
| * MethodHandle[] accumulatorClause = new MethodHandle[]{MH_one, MH_mult, MH_pred, MH_fin}; |
| * MethodHandle loop = MethodHandles.loop(instanceClause, counterClause, accumulatorClause); |
| * assertEquals(5040, loop.invoke(7)); |
| * }</pre></blockquote> |
| * |
| * @param clauses an array of arrays (4-tuples) of {@link MethodHandle}s adhering to the rules described above. |
| * |
| * @return a method handle embodying the looping behavior as defined by the arguments. |
| * |
| * @throws IllegalArgumentException in case any of the constraints described above is violated. |
| * |
| * @see MethodHandles#whileLoop(MethodHandle, MethodHandle, MethodHandle) |
| * @see MethodHandles#doWhileLoop(MethodHandle, MethodHandle, MethodHandle) |
| * @see MethodHandles#countedLoop(MethodHandle, MethodHandle, MethodHandle) |
| * @see MethodHandles#iteratedLoop(MethodHandle, MethodHandle, MethodHandle) |
| * @since 9 |
| */ |
| public static MethodHandle loop(MethodHandle[]... clauses) { |
| // Step 0: determine clause structure. |
| loopChecks0(clauses); |
| |
| List<MethodHandle> init = new ArrayList<>(); |
| List<MethodHandle> step = new ArrayList<>(); |
| List<MethodHandle> pred = new ArrayList<>(); |
| List<MethodHandle> fini = new ArrayList<>(); |
| |
| Stream.of(clauses).filter(c -> Stream.of(c).anyMatch(Objects::nonNull)).forEach(clause -> { |
| init.add(clause[0]); // all clauses have at least length 1 |
| step.add(clause.length <= 1 ? null : clause[1]); |
| pred.add(clause.length <= 2 ? null : clause[2]); |
| fini.add(clause.length <= 3 ? null : clause[3]); |
| }); |
| |
| assert Stream.of(init, step, pred, fini).map(List::size).distinct().count() == 1; |
| final int nclauses = init.size(); |
| |
| // Step 1A: determine iteration variables (V...). |
| final List<Class<?>> iterationVariableTypes = new ArrayList<>(); |
| for (int i = 0; i < nclauses; ++i) { |
| MethodHandle in = init.get(i); |
| MethodHandle st = step.get(i); |
| if (in == null && st == null) { |
| iterationVariableTypes.add(void.class); |
| } else if (in != null && st != null) { |
| loopChecks1a(i, in, st); |
| iterationVariableTypes.add(in.type().returnType()); |
| } else { |
| iterationVariableTypes.add(in == null ? st.type().returnType() : in.type().returnType()); |
| } |
| } |
| final List<Class<?>> commonPrefix = iterationVariableTypes.stream().filter(t -> t != void.class). |
| collect(Collectors.toList()); |
| |
| // Step 1B: determine loop parameters (A...). |
| final List<Class<?>> commonSuffix = buildCommonSuffix(init, step, pred, fini, commonPrefix.size()); |
| loopChecks1b(init, commonSuffix); |
| |
| // Step 1C: determine loop return type. |
| // Step 1D: check other types. |
| // local variable required here; see JDK-8223553 |
| Stream<Class<?>> cstream = fini.stream().filter(Objects::nonNull).map(MethodHandle::type) |
| .map(MethodType::returnType); |
| final Class<?> loopReturnType = cstream.findFirst().orElse(void.class); |
| loopChecks1cd(pred, fini, loopReturnType); |
| |
| // Step 2: determine parameter lists. |
| final List<Class<?>> commonParameterSequence = new ArrayList<>(commonPrefix); |
| commonParameterSequence.addAll(commonSuffix); |
| loopChecks2(step, pred, fini, commonParameterSequence); |
| |
| // Step 3: fill in omitted functions. |
| for (int i = 0; i < nclauses; ++i) { |
| Class<?> t = iterationVariableTypes.get(i); |
| if (init.get(i) == null) { |
| init.set(i, empty(methodType(t, commonSuffix))); |
| } |
| if (step.get(i) == null) { |
| step.set(i, dropArgumentsToMatch(identityOrVoid(t), 0, commonParameterSequence, i)); |
| } |
| if (pred.get(i) == null) { |
| pred.set(i, dropArguments0(constant(boolean.class, true), 0, commonParameterSequence)); |
| } |
| if (fini.get(i) == null) { |
| fini.set(i, empty(methodType(t, commonParameterSequence))); |
| } |
| } |
| |
| // Step 4: fill in missing parameter types. |
| // Also convert all handles to fixed-arity handles. |
| List<MethodHandle> finit = fixArities(fillParameterTypes(init, commonSuffix)); |
| List<MethodHandle> fstep = fixArities(fillParameterTypes(step, commonParameterSequence)); |
| List<MethodHandle> fpred = fixArities(fillParameterTypes(pred, commonParameterSequence)); |
| List<MethodHandle> ffini = fixArities(fillParameterTypes(fini, commonParameterSequence)); |
| |
| assert finit.stream().map(MethodHandle::type).map(MethodType::parameterList). |
| allMatch(pl -> pl.equals(commonSuffix)); |
| assert Stream.of(fstep, fpred, ffini).flatMap(List::stream).map(MethodHandle::type).map(MethodType::parameterList). |
| allMatch(pl -> pl.equals(commonParameterSequence)); |
| |
| // Android-changed: transformer implementation. |
| // return MethodHandleImpl.makeLoop(loopReturnType, commonSuffix, finit, fstep, fpred, ffini); |
| return new Transformers.Loop(loopReturnType, |
| commonSuffix, |
| finit.toArray(MethodHandle[]::new), |
| fstep.toArray(MethodHandle[]::new), |
| fpred.toArray(MethodHandle[]::new), |
| ffini.toArray(MethodHandle[]::new)); |
| } |
| |
| private static void loopChecks0(MethodHandle[][] clauses) { |
| if (clauses == null || clauses.length == 0) { |
| throw newIllegalArgumentException("null or no clauses passed"); |
| } |
| if (Stream.of(clauses).anyMatch(Objects::isNull)) { |
| throw newIllegalArgumentException("null clauses are not allowed"); |
| } |
| if (Stream.of(clauses).anyMatch(c -> c.length > 4)) { |
| throw newIllegalArgumentException("All loop clauses must be represented as MethodHandle arrays with at most 4 elements."); |
| } |
| } |
| |
| private static void loopChecks1a(int i, MethodHandle in, MethodHandle st) { |
| if (in.type().returnType() != st.type().returnType()) { |
| throw misMatchedTypes("clause " + i + ": init and step return types", in.type().returnType(), |
| st.type().returnType()); |
| } |
| } |
| |
| private static List<Class<?>> longestParameterList(Stream<MethodHandle> mhs, int skipSize) { |
| final List<Class<?>> empty = List.of(); |
| final List<Class<?>> longest = mhs.filter(Objects::nonNull). |
| // take only those that can contribute to a common suffix because they are longer than the prefix |
| map(MethodHandle::type). |
| filter(t -> t.parameterCount() > skipSize). |
| map(MethodType::parameterList). |
| reduce((p, q) -> p.size() >= q.size() ? p : q).orElse(empty); |
| return longest.size() == 0 ? empty : longest.subList(skipSize, longest.size()); |
| } |
| |
| private static List<Class<?>> longestParameterList(List<List<Class<?>>> lists) { |
| final List<Class<?>> empty = List.of(); |
| return lists.stream().reduce((p, q) -> p.size() >= q.size() ? p : q).orElse(empty); |
| } |
| |
| private static List<Class<?>> buildCommonSuffix(List<MethodHandle> init, List<MethodHandle> step, List<MethodHandle> pred, List<MethodHandle> fini, int cpSize) { |
| final List<Class<?>> longest1 = longestParameterList(Stream.of(step, pred, fini).flatMap(List::stream), cpSize); |
| final List<Class<?>> longest2 = longestParameterList(init.stream(), 0); |
| return longestParameterList(Arrays.asList(longest1, longest2)); |
| } |
| |
| private static void loopChecks1b(List<MethodHandle> init, List<Class<?>> commonSuffix) { |
| if (init.stream().filter(Objects::nonNull).map(MethodHandle::type). |
| anyMatch(t -> !t.effectivelyIdenticalParameters(0, commonSuffix))) { |
| throw newIllegalArgumentException("found non-effectively identical init parameter type lists: " + init + |
| " (common suffix: " + commonSuffix + ")"); |
| } |
| } |
| |
| private static void loopChecks1cd(List<MethodHandle> pred, List<MethodHandle> fini, Class<?> loopReturnType) { |
| if (fini.stream().filter(Objects::nonNull).map(MethodHandle::type).map(MethodType::returnType). |
| anyMatch(t -> t != loopReturnType)) { |
| throw newIllegalArgumentException("found non-identical finalizer return types: " + fini + " (return type: " + |
| loopReturnType + ")"); |
| } |
| |
| if (!pred.stream().filter(Objects::nonNull).findFirst().isPresent()) { |
| throw newIllegalArgumentException("no predicate found", pred); |
| } |
| if (pred.stream().filter(Objects::nonNull).map(MethodHandle::type).map(MethodType::returnType). |
| anyMatch(t -> t != boolean.class)) { |
| throw newIllegalArgumentException("predicates must have boolean return type", pred); |
| } |
| } |
| |
| private static void loopChecks2(List<MethodHandle> step, List<MethodHandle> pred, List<MethodHandle> fini, List<Class<?>> commonParameterSequence) { |
| if (Stream.of(step, pred, fini).flatMap(List::stream).filter(Objects::nonNull).map(MethodHandle::type). |
| anyMatch(t -> !t.effectivelyIdenticalParameters(0, commonParameterSequence))) { |
| throw newIllegalArgumentException("found non-effectively identical parameter type lists:\nstep: " + step + |
| "\npred: " + pred + "\nfini: " + fini + " (common parameter sequence: " + commonParameterSequence + ")"); |
| } |
| } |
| |
| private static List<MethodHandle> fillParameterTypes(List<MethodHandle> hs, final List<Class<?>> targetParams) { |
| return hs.stream().map(h -> { |
| int pc = h.type().parameterCount(); |
| int tpsize = targetParams.size(); |
| return pc < tpsize ? dropArguments0(h, pc, targetParams.subList(pc, tpsize)) : h; |
| }).collect(Collectors.toList()); |
| } |
| |
| private static List<MethodHandle> fixArities(List<MethodHandle> hs) { |
| return hs.stream().map(MethodHandle::asFixedArity).collect(Collectors.toList()); |
| } |
| |
| /** |
| * Constructs a {@code while} loop from an initializer, a body, and a predicate. |
| * This is a convenience wrapper for the {@linkplain #loop(MethodHandle[][]) generic loop combinator}. |
| * <p> |
| * The {@code pred} handle describes the loop condition; and {@code body}, its body. The loop resulting from this |
| * method will, in each iteration, first evaluate the predicate and then execute its body (if the predicate |
| * evaluates to {@code true}). |
| * The loop will terminate once the predicate evaluates to {@code false} (the body will not be executed in this case). |
| * <p> |
| * The {@code init} handle describes the initial value of an additional optional loop-local variable. |
| * In each iteration, this loop-local variable, if present, will be passed to the {@code body} |
| * and updated with the value returned from its invocation. The result of loop execution will be |
| * the final value of the additional loop-local variable (if present). |
| * <p> |
| * The following rules hold for these argument handles:<ul> |
| * <li>The {@code body} handle must not be {@code null}; its type must be of the form |
| * {@code (V A...)V}, where {@code V} is non-{@code void}, or else {@code (A...)void}. |
| * (In the {@code void} case, we assign the type {@code void} to the name {@code V}, |
| * and we will write {@code (V A...)V} with the understanding that a {@code void} type {@code V} |
| * is quietly dropped from the parameter list, leaving {@code (A...)V}.) |
| * <li>The parameter list {@code (V A...)} of the body is called the <em>internal parameter list</em>. |
| * It will constrain the parameter lists of the other loop parts. |
| * <li>If the iteration variable type {@code V} is dropped from the internal parameter list, the resulting shorter |
| * list {@code (A...)} is called the <em>external parameter list</em>. |
| * <li>The body return type {@code V}, if non-{@code void}, determines the type of an |
| * additional state variable of the loop. |
| * The body must both accept and return a value of this type {@code V}. |
| * <li>If {@code init} is non-{@code null}, it must have return type {@code V}. |
| * Its parameter list (of some <a href="MethodHandles.html#astar">form {@code (A*)}</a>) must be |
| * <a href="MethodHandles.html#effid">effectively identical</a> |
| * to the external parameter list {@code (A...)}. |
| * <li>If {@code init} is {@code null}, the loop variable will be initialized to its |
| * {@linkplain #empty default value}. |
| * <li>The {@code pred} handle must not be {@code null}. It must have {@code boolean} as its return type. |
| * Its parameter list (either empty or of the form {@code (V A*)}) must be |
| * effectively identical to the internal parameter list. |
| * </ul> |
| * <p> |
| * The resulting loop handle's result type and parameter signature are determined as follows:<ul> |
| * <li>The loop handle's result type is the result type {@code V} of the body. |
| * <li>The loop handle's parameter types are the types {@code (A...)}, |
| * from the external parameter list. |
| * </ul> |
| * <p> |
| * Here is pseudocode for the resulting loop handle. In the code, {@code V}/{@code v} represent the type / value of |
| * the sole loop variable as well as the result type of the loop; and {@code A}/{@code a}, that of the argument |
| * passed to the loop. |
| * <blockquote><pre>{@code |
| * V init(A...); |
| * boolean pred(V, A...); |
| * V body(V, A...); |
| * V whileLoop(A... a...) { |
| * V v = init(a...); |
| * while (pred(v, a...)) { |
| * v = body(v, a...); |
| * } |
| * return v; |
| * } |
| * }</pre></blockquote> |
| * |
| * @apiNote Example: |
| * <blockquote><pre>{@code |
| * // implement the zip function for lists as a loop handle |
| * static List<String> initZip(Iterator<String> a, Iterator<String> b) { return new ArrayList<>(); } |
| * static boolean zipPred(List<String> zip, Iterator<String> a, Iterator<String> b) { return a.hasNext() && b.hasNext(); } |
| * static List<String> zipStep(List<String> zip, Iterator<String> a, Iterator<String> b) { |
| * zip.add(a.next()); |
| * zip.add(b.next()); |
| * return zip; |
| * } |
| * // assume MH_initZip, MH_zipPred, and MH_zipStep are handles to the above methods |
| * MethodHandle loop = MethodHandles.whileLoop(MH_initZip, MH_zipPred, MH_zipStep); |
| * List<String> a = Arrays.asList("a", "b", "c", "d"); |
| * List<String> b = Arrays.asList("e", "f", "g", "h"); |
| * List<String> zipped = Arrays.asList("a", "e", "b", "f", "c", "g", "d", "h"); |
| * assertEquals(zipped, (List<String>) loop.invoke(a.iterator(), b.iterator())); |
| * }</pre></blockquote> |
| * |
| * |
| * @apiNote The implementation of this method can be expressed as follows: |
| * <blockquote><pre>{@code |
| * MethodHandle whileLoop(MethodHandle init, MethodHandle pred, MethodHandle body) { |
| * MethodHandle fini = (body.type().returnType() == void.class |
| * ? null : identity(body.type().returnType())); |
| * MethodHandle[] |
| * checkExit = { null, null, pred, fini }, |
| * varBody = { init, body }; |
| * return loop(checkExit, varBody); |
| * } |
| * }</pre></blockquote> |
| * |
| * @param init optional initializer, providing the initial value of the loop variable. |
| * May be {@code null}, implying a default initial value. See above for other constraints. |
| * @param pred condition for the loop, which may not be {@code null}. Its result type must be {@code boolean}. See |
| * above for other constraints. |
| * @param body body of the loop, which may not be {@code null}. It controls the loop parameters and result type. |
| * See above for other constraints. |
| * |
| * @return a method handle implementing the {@code while} loop as described by the arguments. |
| * @throws IllegalArgumentException if the rules for the arguments are violated. |
| * @throws NullPointerException if {@code pred} or {@code body} are {@code null}. |
| * |
| * @see #loop(MethodHandle[][]) |
| * @see #doWhileLoop(MethodHandle, MethodHandle, MethodHandle) |
| * @since 9 |
| */ |
| public static MethodHandle whileLoop(MethodHandle init, MethodHandle pred, MethodHandle body) { |
| whileLoopChecks(init, pred, body); |
| MethodHandle fini = identityOrVoid(body.type().returnType()); |
| MethodHandle[] checkExit = { null, null, pred, fini }; |
| MethodHandle[] varBody = { init, body }; |
| return loop(checkExit, varBody); |
| } |
| |
| /** |
| * Constructs a {@code do-while} loop from an initializer, a body, and a predicate. |
| * This is a convenience wrapper for the {@linkplain #loop(MethodHandle[][]) generic loop combinator}. |
| * <p> |
| * The {@code pred} handle describes the loop condition; and {@code body}, its body. The loop resulting from this |
| * method will, in each iteration, first execute its body and then evaluate the predicate. |
| * The loop will terminate once the predicate evaluates to {@code false} after an execution of the body. |
| * <p> |
| * The {@code init} handle describes the initial value of an additional optional loop-local variable. |
| * In each iteration, this loop-local variable, if present, will be passed to the {@code body} |
| * and updated with the value returned from its invocation. The result of loop execution will be |
| * the final value of the additional loop-local variable (if present). |
| * <p> |
| * The following rules hold for these argument handles:<ul> |
| * <li>The {@code body} handle must not be {@code null}; its type must be of the form |
| * {@code (V A...)V}, where {@code V} is non-{@code void}, or else {@code (A...)void}. |
| * (In the {@code void} case, we assign the type {@code void} to the name {@code V}, |
| * and we will write {@code (V A...)V} with the understanding that a {@code void} type {@code V} |
| * is quietly dropped from the parameter list, leaving {@code (A...)V}.) |
| * <li>The parameter list {@code (V A...)} of the body is called the <em>internal parameter list</em>. |
| * It will constrain the parameter lists of the other loop parts. |
| * <li>If the iteration variable type {@code V} is dropped from the internal parameter list, the resulting shorter |
| * list {@code (A...)} is called the <em>external parameter list</em>. |
| * <li>The body return type {@code V}, if non-{@code void}, determines the type of an |
| * additional state variable of the loop. |
| * The body must both accept and return a value of this type {@code V}. |
| * <li>If {@code init} is non-{@code null}, it must have return type {@code V}. |
| * Its parameter list (of some <a href="MethodHandles.html#astar">form {@code (A*)}</a>) must be |
| * <a href="MethodHandles.html#effid">effectively identical</a> |
| * to the external parameter list {@code (A...)}. |
| * <li>If {@code init} is {@code null}, the loop variable will be initialized to its |
| * {@linkplain #empty default value}. |
| * <li>The {@code pred} handle must not be {@code null}. It must have {@code boolean} as its return type. |
| * Its parameter list (either empty or of the form {@code (V A*)}) must be |
| * effectively identical to the internal parameter list. |
| * </ul> |
| * <p> |
| * The resulting loop handle's result type and parameter signature are determined as follows:<ul> |
| * <li>The loop handle's result type is the result type {@code V} of the body. |
| * <li>The loop handle's parameter types are the types {@code (A...)}, |
| * from the external parameter list. |
| * </ul> |
| * <p> |
| * Here is pseudocode for the resulting loop handle. In the code, {@code V}/{@code v} represent the type / value of |
| * the sole loop variable as well as the result type of the loop; and {@code A}/{@code a}, that of the argument |
| * passed to the loop. |
| * <blockquote><pre>{@code |
| * V init(A...); |
| * boolean pred(V, A...); |
| * V body(V, A...); |
| * V doWhileLoop(A... a...) { |
| * V v = init(a...); |
| * do { |
| * v = body(v, a...); |
| * } while (pred(v, a...)); |
| * return v; |
| * } |
| * }</pre></blockquote> |
| * |
| * @apiNote Example: |
| * <blockquote><pre>{@code |
| * // int i = 0; while (i < limit) { ++i; } return i; => limit |
| * static int zero(int limit) { return 0; } |
| * static int step(int i, int limit) { return i + 1; } |
| * static boolean pred(int i, int limit) { return i < limit; } |
| * // assume MH_zero, MH_step, and MH_pred are handles to the above methods |
| * MethodHandle loop = MethodHandles.doWhileLoop(MH_zero, MH_step, MH_pred); |
| * assertEquals(23, loop.invoke(23)); |
| * }</pre></blockquote> |
| * |
| * |
| * @apiNote The implementation of this method can be expressed as follows: |
| * <blockquote><pre>{@code |
| * MethodHandle doWhileLoop(MethodHandle init, MethodHandle body, MethodHandle pred) { |
| * MethodHandle fini = (body.type().returnType() == void.class |
| * ? null : identity(body.type().returnType())); |
| * MethodHandle[] clause = { init, body, pred, fini }; |
| * return loop(clause); |
| * } |
| * }</pre></blockquote> |
| * |
| * @param init optional initializer, providing the initial value of the loop variable. |
| * May be {@code null}, implying a default initial value. See above for other constraints. |
| * @param body body of the loop, which may not be {@code null}. It controls the loop parameters and result type. |
| * See above for other constraints. |
| * @param pred condition for the loop, which may not be {@code null}. Its result type must be {@code boolean}. See |
| * above for other constraints. |
| * |
| * @return a method handle implementing the {@code while} loop as described by the arguments. |
| * @throws IllegalArgumentException if the rules for the arguments are violated. |
| * @throws NullPointerException if {@code pred} or {@code body} are {@code null}. |
| * |
| * @see #loop(MethodHandle[][]) |
| * @see #whileLoop(MethodHandle, MethodHandle, MethodHandle) |
| * @since 9 |
| */ |
| public static MethodHandle doWhileLoop(MethodHandle init, MethodHandle body, MethodHandle pred) { |
| whileLoopChecks(init, pred, body); |
| MethodHandle fini = identityOrVoid(body.type().returnType()); |
| MethodHandle[] clause = {init, body, pred, fini }; |
| return loop(clause); |
| } |
| |
| private static void whileLoopChecks(MethodHandle init, MethodHandle pred, MethodHandle body) { |
| Objects.requireNonNull(pred); |
| Objects.requireNonNull(body); |
| MethodType bodyType = body.type(); |
| Class<?> returnType = bodyType.returnType(); |
| List<Class<?>> innerList = bodyType.parameterList(); |
| List<Class<?>> outerList = innerList; |
| if (returnType == void.class) { |
| // OK |
| } else if (innerList.size() == 0 || innerList.get(0) != returnType) { |
| // leading V argument missing => error |
| MethodType expected = bodyType.insertParameterTypes(0, returnType); |
| throw misMatchedTypes("body function", bodyType, expected); |
| } else { |
| outerList = innerList.subList(1, innerList.size()); |
| } |
| MethodType predType = pred.type(); |
| if (predType.returnType() != boolean.class || |
| !predType.effectivelyIdenticalParameters(0, innerList)) { |
| throw misMatchedTypes("loop predicate", predType, methodType(boolean.class, innerList)); |
| } |
| if (init != null) { |
| MethodType initType = init.type(); |
| if (initType.returnType() != returnType || |
| !initType.effectivelyIdenticalParameters(0, outerList)) { |
| throw misMatchedTypes("loop initializer", initType, methodType(returnType, outerList)); |
| } |
| } |
| } |
| |
| /** |
| * Constructs a loop that runs a given number of iterations. |
| * This is a convenience wrapper for the {@linkplain #loop(MethodHandle[][]) generic loop combinator}. |
| * <p> |
| * The number of iterations is determined by the {@code iterations} handle evaluation result. |
| * The loop counter {@code i} is an extra loop iteration variable of type {@code int}. |
| * It will be initialized to 0 and incremented by 1 in each iteration. |
| * <p> |
| * If the {@code body} handle returns a non-{@code void} type {@code V}, a leading loop iteration variable |
| * of that type is also present. This variable is initialized using the optional {@code init} handle, |
| * or to the {@linkplain #empty default value} of type {@code V} if that handle is {@code null}. |
| * <p> |
| * In each iteration, the iteration variables are passed to an invocation of the {@code body} handle. |
| * A non-{@code void} value returned from the body (of type {@code V}) updates the leading |
| * iteration variable. |
| * The result of the loop handle execution will be the final {@code V} value of that variable |
| * (or {@code void} if there is no {@code V} variable). |
| * <p> |
| * The following rules hold for the argument handles:<ul> |
| * <li>The {@code iterations} handle must not be {@code null}, and must return |
| * the type {@code int}, referred to here as {@code I} in parameter type lists. |
| * <li>The {@code body} handle must not be {@code null}; its type must be of the form |
| * {@code (V I A...)V}, where {@code V} is non-{@code void}, or else {@code (I A...)void}. |
| * (In the {@code void} case, we assign the type {@code void} to the name {@code V}, |
| * and we will write {@code (V I A...)V} with the understanding that a {@code void} type {@code V} |
| * is quietly dropped from the parameter list, leaving {@code (I A...)V}.) |
| * <li>The parameter list {@code (V I A...)} of the body contributes to a list |
| * of types called the <em>internal parameter list</em>. |
| * It will constrain the parameter lists of the other loop parts. |
| * <li>As a special case, if the body contributes only {@code V} and {@code I} types, |
| * with no additional {@code A} types, then the internal parameter list is extended by |
| * the argument types {@code A...} of the {@code iterations} handle. |
| * <li>If the iteration variable types {@code (V I)} are dropped from the internal parameter list, the resulting shorter |
| * list {@code (A...)} is called the <em>external parameter list</em>. |
| * <li>The body return type {@code V}, if non-{@code void}, determines the type of an |
| * additional state variable of the loop. |
| * The body must both accept a leading parameter and return a value of this type {@code V}. |
| * <li>If {@code init} is non-{@code null}, it must have return type {@code V}. |
| * Its parameter list (of some <a href="MethodHandles.html#astar">form {@code (A*)}</a>) must be |
| * <a href="MethodHandles.html#effid">effectively identical</a> |
| * to the external parameter list {@code (A...)}. |
| * <li>If {@code init} is {@code null}, the loop variable will be initialized to its |
| * {@linkplain #empty default value}. |
| * <li>The parameter list of {@code iterations} (of some form {@code (A*)}) must be |
| * effectively identical to the external parameter list {@code (A...)}. |
| * </ul> |
| * <p> |
| * The resulting loop handle's result type and parameter signature are determined as follows:<ul> |
| * <li>The loop handle's result type is the result type {@code V} of the body. |
| * <li>The loop handle's parameter types are the types {@code (A...)}, |
| * from the external parameter list. |
| * </ul> |
| * <p> |
| * Here is pseudocode for the resulting loop handle. In the code, {@code V}/{@code v} represent the type / value of |
| * the second loop variable as well as the result type of the loop; and {@code A...}/{@code a...} represent |
| * arguments passed to the loop. |
| * <blockquote><pre>{@code |
| * int iterations(A...); |
| * V init(A...); |
| * V body(V, int, A...); |
| * V countedLoop(A... a...) { |
| * int end = iterations(a...); |
| * V v = init(a...); |
| * for (int i = 0; i < end; ++i) { |
| * v = body(v, i, a...); |
| * } |
| * return v; |
| * } |
| * }</pre></blockquote> |
| * |
| * @apiNote Example with a fully conformant body method: |
| * <blockquote><pre>{@code |
| * // String s = "Lambdaman!"; for (int i = 0; i < 13; ++i) { s = "na " + s; } return s; |
| * // => a variation on a well known theme |
| * static String step(String v, int counter, String init) { return "na " + v; } |
| * // assume MH_step is a handle to the method above |
| * MethodHandle fit13 = MethodHandles.constant(int.class, 13); |
| * MethodHandle start = MethodHandles.identity(String.class); |
| * MethodHandle loop = MethodHandles.countedLoop(fit13, start, MH_step); |
| * assertEquals("na na na na na na na na na na na na na Lambdaman!", loop.invoke("Lambdaman!")); |
| * }</pre></blockquote> |
| * |
| * @apiNote Example with the simplest possible body method type, |
| * and passing the number of iterations to the loop invocation: |
| * <blockquote><pre>{@code |
| * // String s = "Lambdaman!"; for (int i = 0; i < 13; ++i) { s = "na " + s; } return s; |
| * // => a variation on a well known theme |
| * static String step(String v, int counter ) { return "na " + v; } |
| * // assume MH_step is a handle to the method above |
| * MethodHandle count = MethodHandles.dropArguments(MethodHandles.identity(int.class), 1, String.class); |
| * MethodHandle start = MethodHandles.dropArguments(MethodHandles.identity(String.class), 0, int.class); |
| * MethodHandle loop = MethodHandles.countedLoop(count, start, MH_step); // (v, i) -> "na " + v |
| * assertEquals("na na na na na na na na na na na na na Lambdaman!", loop.invoke(13, "Lambdaman!")); |
| * }</pre></blockquote> |
| * |
| * @apiNote Example that treats the number of iterations, string to append to, and string to append |
| * as loop parameters: |
| * <blockquote><pre>{@code |
| * // String s = "Lambdaman!", t = "na"; for (int i = 0; i < 13; ++i) { s = t + " " + s; } return s; |
| * // => a variation on a well known theme |
| * static String step(String v, int counter, int iterations_, String pre, String start_) { return pre + " " + v; } |
| * // assume MH_step is a handle to the method above |
| * MethodHandle count = MethodHandles.identity(int.class); |
| * MethodHandle start = MethodHandles.dropArguments(MethodHandles.identity(String.class), 0, int.class, String.class); |
| * MethodHandle loop = MethodHandles.countedLoop(count, start, MH_step); // (v, i, _, pre, _) -> pre + " " + v |
| * assertEquals("na na na na na na na na na na na na na Lambdaman!", loop.invoke(13, "na", "Lambdaman!")); |
| * }</pre></blockquote> |
| * |
| * @apiNote Example that illustrates the usage of {@link #dropArgumentsToMatch(MethodHandle, int, List, int)} |
| * to enforce a loop type: |
| * <blockquote><pre>{@code |
| * // String s = "Lambdaman!", t = "na"; for (int i = 0; i < 13; ++i) { s = t + " " + s; } return s; |
| * // => a variation on a well known theme |
| * static String step(String v, int counter, String pre) { return pre + " " + v; } |
| * // assume MH_step is a handle to the method above |
| * MethodType loopType = methodType(String.class, String.class, int.class, String.class); |
| * MethodHandle count = MethodHandles.dropArgumentsToMatch(MethodHandles.identity(int.class), 0, loopType.parameterList(), 1); |
| * MethodHandle start = MethodHandles.dropArgumentsToMatch(MethodHandles.identity(String.class), 0, loopType.parameterList(), 2); |
| * MethodHandle body = MethodHandles.dropArgumentsToMatch(MH_step, 2, loopType.parameterList(), 0); |
| * MethodHandle loop = MethodHandles.countedLoop(count, start, body); // (v, i, pre, _, _) -> pre + " " + v |
| * assertEquals("na na na na na na na na na na na na na Lambdaman!", loop.invoke("na", 13, "Lambdaman!")); |
| * }</pre></blockquote> |
| * |
| * @apiNote The implementation of this method can be expressed as follows: |
| * <blockquote><pre>{@code |
| * MethodHandle countedLoop(MethodHandle iterations, MethodHandle init, MethodHandle body) { |
| * return countedLoop(empty(iterations.type()), iterations, init, body); |
| * } |
| * }</pre></blockquote> |
| * |
| * @param iterations a non-{@code null} handle to return the number of iterations this loop should run. The handle's |
| * result type must be {@code int}. See above for other constraints. |
| * @param init optional initializer, providing the initial value of the loop variable. |
| * May be {@code null}, implying a default initial value. See above for other constraints. |
| * @param body body of the loop, which may not be {@code null}. |
| * It controls the loop parameters and result type in the standard case (see above for details). |
| * It must accept its own return type (if non-void) plus an {@code int} parameter (for the counter), |
| * and may accept any number of additional types. |
| * See above for other constraints. |
| * |
| * @return a method handle representing the loop. |
| * @throws NullPointerException if either of the {@code iterations} or {@code body} handles is {@code null}. |
| * @throws IllegalArgumentException if any argument violates the rules formulated above. |
| * |
| * @see #countedLoop(MethodHandle, MethodHandle, MethodHandle, MethodHandle) |
| * @since 9 |
| */ |
| public static MethodHandle countedLoop(MethodHandle iterations, MethodHandle init, MethodHandle body) { |
| return countedLoop(empty(iterations.type()), iterations, init, body); |
| } |
| |
| /** |
| * Constructs a loop that counts over a range of numbers. |
| * This is a convenience wrapper for the {@linkplain #loop(MethodHandle[][]) generic loop combinator}. |
| * <p> |
| * The loop counter {@code i} is a loop iteration variable of type {@code int}. |
| * The {@code start} and {@code end} handles determine the start (inclusive) and end (exclusive) |
| * values of the loop counter. |
| * The loop counter will be initialized to the {@code int} value returned from the evaluation of the |
| * {@code start} handle and run to the value returned from {@code end} (exclusively) with a step width of 1. |
| * <p> |
| * If the {@code body} handle returns a non-{@code void} type {@code V}, a leading loop iteration variable |
| * of that type is also present. This variable is initialized using the optional {@code init} handle, |
| * or to the {@linkplain #empty default value} of type {@code V} if that handle is {@code null}. |
| * <p> |
| * In each iteration, the iteration variables are passed to an invocation of the {@code body} handle. |
| * A non-{@code void} value returned from the body (of type {@code V}) updates the leading |
| * iteration variable. |
| * The result of the loop handle execution will be the final {@code V} value of that variable |
| * (or {@code void} if there is no {@code V} variable). |
| * <p> |
| * The following rules hold for the argument handles:<ul> |
| * <li>The {@code start} and {@code end} handles must not be {@code null}, and must both return |
| * the common type {@code int}, referred to here as {@code I} in parameter type lists. |
| * <li>The {@code body} handle must not be {@code null}; its type must be of the form |
| * {@code (V I A...)V}, where {@code V} is non-{@code void}, or else {@code (I A...)void}. |
| * (In the {@code void} case, we assign the type {@code void} to the name {@code V}, |
| * and we will write {@code (V I A...)V} with the understanding that a {@code void} type {@code V} |
| * is quietly dropped from the parameter list, leaving {@code (I A...)V}.) |
| * <li>The parameter list {@code (V I A...)} of the body contributes to a list |
| * of types called the <em>internal parameter list</em>. |
| * It will constrain the parameter lists of the other loop parts. |
| * <li>As a special case, if the body contributes only {@code V} and {@code I} types, |
| * with no additional {@code A} types, then the internal parameter list is extended by |
| * the argument types {@code A...} of the {@code end} handle. |
| * <li>If the iteration variable types {@code (V I)} are dropped from the internal parameter list, the resulting shorter |
| * list {@code (A...)} is called the <em>external parameter list</em>. |
| * <li>The body return type {@code V}, if non-{@code void}, determines the type of an |
| * additional state variable of the loop. |
| * The body must both accept a leading parameter and return a value of this type {@code V}. |
| * <li>If {@code init} is non-{@code null}, it must have return type {@code V}. |
| * Its parameter list (of some <a href="MethodHandles.html#astar">form {@code (A*)}</a>) must be |
| * <a href="MethodHandles.html#effid">effectively identical</a> |
| * to the external parameter list {@code (A...)}. |
| * <li>If {@code init} is {@code null}, the loop variable will be initialized to its |
| * {@linkplain #empty default value}. |
| * <li>The parameter list of {@code start} (of some form {@code (A*)}) must be |
| * effectively identical to the external parameter list {@code (A...)}. |
| * <li>Likewise, the parameter list of {@code end} must be effectively identical |
| * to the external parameter list. |
| * </ul> |
| * <p> |
| * The resulting loop handle's result type and parameter signature are determined as follows:<ul> |
| * <li>The loop handle's result type is the result type {@code V} of the body. |
| * <li>The loop handle's parameter types are the types {@code (A...)}, |
| * from the external parameter list. |
| * </ul> |
| * <p> |
| * Here is pseudocode for the resulting loop handle. In the code, {@code V}/{@code v} represent the type / value of |
| * the second loop variable as well as the result type of the loop; and {@code A...}/{@code a...} represent |
| * arguments passed to the loop. |
| * <blockquote><pre>{@code |
| * int start(A...); |
| * int end(A...); |
| * V init(A...); |
| * V body(V, int, A...); |
| * V countedLoop(A... a...) { |
| * int e = end(a...); |
| * int s = start(a...); |
| * V v = init(a...); |
| * for (int i = s; i < e; ++i) { |
| * v = body(v, i, a...); |
| * } |
| * return v; |
| * } |
| * }</pre></blockquote> |
| * |
| * @apiNote The implementation of this method can be expressed as follows: |
| * <blockquote><pre>{@code |
| * MethodHandle countedLoop(MethodHandle start, MethodHandle end, MethodHandle init, MethodHandle body) { |
| * MethodHandle returnVar = dropArguments(identity(init.type().returnType()), 0, int.class, int.class); |
| * // assume MH_increment and MH_predicate are handles to implementation-internal methods with |
| * // the following semantics: |
| * // MH_increment: (int limit, int counter) -> counter + 1 |
| * // MH_predicate: (int limit, int counter) -> counter < limit |
| * Class<?> counterType = start.type().returnType(); // int |
| * Class<?> returnType = body.type().returnType(); |
| * MethodHandle incr = MH_increment, pred = MH_predicate, retv = null; |
| * if (returnType != void.class) { // ignore the V variable |
| * incr = dropArguments(incr, 1, returnType); // (limit, v, i) => (limit, i) |
| * pred = dropArguments(pred, 1, returnType); // ditto |
| * retv = dropArguments(identity(returnType), 0, counterType); // ignore limit |
| * } |
| * body = dropArguments(body, 0, counterType); // ignore the limit variable |
| * MethodHandle[] |
| * loopLimit = { end, null, pred, retv }, // limit = end(); i < limit || return v |
| * bodyClause = { init, body }, // v = init(); v = body(v, i) |
| * indexVar = { start, incr }; // i = start(); i = i + 1 |
| * return loop(loopLimit, bodyClause, indexVar); |
| * } |
| * }</pre></blockquote> |
| * |
| * @param start a non-{@code null} handle to return the start value of the loop counter, which must be {@code int}. |
| * See above for other constraints. |
| * @param end a non-{@code null} handle to return the end value of the loop counter (the loop will run to |
| * {@code end-1}). The result type must be {@code int}. See above for other constraints. |
| * @param init optional initializer, providing the initial value of the loop variable. |
| * May be {@code null}, implying a default initial value. See above for other constraints. |
| * @param body body of the loop, which may not be {@code null}. |
| * It controls the loop parameters and result type in the standard case (see above for details). |
| * It must accept its own return type (if non-void) plus an {@code int} parameter (for the counter), |
| * and may accept any number of additional types. |
| * See above for other constraints. |
| * |
| * @return a method handle representing the loop. |
| * @throws NullPointerException if any of the {@code start}, {@code end}, or {@code body} handles is {@code null}. |
| * @throws IllegalArgumentException if any argument violates the rules formulated above. |
| * |
| * @see #countedLoop(MethodHandle, MethodHandle, MethodHandle) |
| * @since 9 |
| */ |
| public static MethodHandle countedLoop(MethodHandle start, MethodHandle end, MethodHandle init, MethodHandle body) { |
| countedLoopChecks(start, end, init, body); |
| Class<?> counterType = start.type().returnType(); // int, but who's counting? |
| Class<?> limitType = end.type().returnType(); // yes, int again |
| Class<?> returnType = body.type().returnType(); |
| // Android-changed: getConstantHandle is in MethodHandles. |
| // MethodHandle incr = MethodHandleImpl.getConstantHandle(MethodHandleImpl.MH_countedLoopStep); |
| // MethodHandle pred = MethodHandleImpl.getConstantHandle(MethodHandleImpl.MH_countedLoopPred); |
| MethodHandle incr = getConstantHandle(MH_countedLoopStep); |
| MethodHandle pred = getConstantHandle(MH_countedLoopPred); |
| MethodHandle retv = null; |
| if (returnType != void.class) { |
| incr = dropArguments(incr, 1, returnType); // (limit, v, i) => (limit, i) |
| pred = dropArguments(pred, 1, returnType); // ditto |
| retv = dropArguments(identity(returnType), 0, counterType); |
| } |
| body = dropArguments(body, 0, counterType); // ignore the limit variable |
| MethodHandle[] |
| loopLimit = { end, null, pred, retv }, // limit = end(); i < limit || return v |
| bodyClause = { init, body }, // v = init(); v = body(v, i) |
| indexVar = { start, incr }; // i = start(); i = i + 1 |
| return loop(loopLimit, bodyClause, indexVar); |
| } |
| |
| private static void countedLoopChecks(MethodHandle start, MethodHandle end, MethodHandle init, MethodHandle body) { |
| Objects.requireNonNull(start); |
| Objects.requireNonNull(end); |
| Objects.requireNonNull(body); |
| Class<?> counterType = start.type().returnType(); |
| if (counterType != int.class) { |
| MethodType expected = start.type().changeReturnType(int.class); |
| throw misMatchedTypes("start function", start.type(), expected); |
| } else if (end.type().returnType() != counterType) { |
| MethodType expected = end.type().changeReturnType(counterType); |
| throw misMatchedTypes("end function", end.type(), expected); |
| } |
| MethodType bodyType = body.type(); |
| Class<?> returnType = bodyType.returnType(); |
| List<Class<?>> innerList = bodyType.parameterList(); |
| // strip leading V value if present |
| int vsize = (returnType == void.class ? 0 : 1); |
| if (vsize != 0 && (innerList.size() == 0 || innerList.get(0) != returnType)) { |
| // argument list has no "V" => error |
| MethodType expected = bodyType.insertParameterTypes(0, returnType); |
| throw misMatchedTypes("body function", bodyType, expected); |
| } else if (innerList.size() <= vsize || innerList.get(vsize) != counterType) { |
| // missing I type => error |
| MethodType expected = bodyType.insertParameterTypes(vsize, counterType); |
| throw misMatchedTypes("body function", bodyType, expected); |
| } |
| List<Class<?>> outerList = innerList.subList(vsize + 1, innerList.size()); |
| if (outerList.isEmpty()) { |
| // special case; take lists from end handle |
| outerList = end.type().parameterList(); |
| innerList = bodyType.insertParameterTypes(vsize + 1, outerList).parameterList(); |
| } |
| MethodType expected = methodType(counterType, outerList); |
| if (!start.type().effectivelyIdenticalParameters(0, outerList)) { |
| throw misMatchedTypes("start parameter types", start.type(), expected); |
| } |
| if (end.type() != start.type() && |
| !end.type().effectivelyIdenticalParameters(0, outerList)) { |
| throw misMatchedTypes("end parameter types", end.type(), expected); |
| } |
| if (init != null) { |
| MethodType initType = init.type(); |
| if (initType.returnType() != returnType || |
| !initType.effectivelyIdenticalParameters(0, outerList)) { |
| throw misMatchedTypes("loop initializer", initType, methodType(returnType, outerList)); |
| } |
| } |
| } |
| |
| /** |
| * Constructs a loop that ranges over the values produced by an {@code Iterator<T>}. |
| * This is a convenience wrapper for the {@linkplain #loop(MethodHandle[][]) generic loop combinator}. |
| * <p> |
| * The iterator itself will be determined by the evaluation of the {@code iterator} handle. |
| * Each value it produces will be stored in a loop iteration variable of type {@code T}. |
| * <p> |
| * If the {@code body} handle returns a non-{@code void} type {@code V}, a leading loop iteration variable |
| * of that type is also present. This variable is initialized using the optional {@code init} handle, |
| * or to the {@linkplain #empty default value} of type {@code V} if that handle is {@code null}. |
| * <p> |
| * In each iteration, the iteration variables are passed to an invocation of the {@code body} handle. |
| * A non-{@code void} value returned from the body (of type {@code V}) updates the leading |
| * iteration variable. |
| * The result of the loop handle execution will be the final {@code V} value of that variable |
| * (or {@code void} if there is no {@code V} variable). |
| * <p> |
| * The following rules hold for the argument handles:<ul> |
| * <li>The {@code body} handle must not be {@code null}; its type must be of the form |
| * {@code (V T A...)V}, where {@code V} is non-{@code void}, or else {@code (T A...)void}. |
| * (In the {@code void} case, we assign the type {@code void} to the name {@code V}, |
| * and we will write {@code (V T A...)V} with the understanding that a {@code void} type {@code V} |
| * is quietly dropped from the parameter list, leaving {@code (T A...)V}.) |
| * <li>The parameter list {@code (V T A...)} of the body contributes to a list |
| * of types called the <em>internal parameter list</em>. |
| * It will constrain the parameter lists of the other loop parts. |
| * <li>As a special case, if the body contributes only {@code V} and {@code T} types, |
| * with no additional {@code A} types, then the internal parameter list is extended by |
| * the argument types {@code A...} of the {@code iterator} handle; if it is {@code null} the |
| * single type {@code Iterable} is added and constitutes the {@code A...} list. |
| * <li>If the iteration variable types {@code (V T)} are dropped from the internal parameter list, the resulting shorter |
| * list {@code (A...)} is called the <em>external parameter list</em>. |
| * <li>The body return type {@code V}, if non-{@code void}, determines the type of an |
| * additional state variable of the loop. |
| * The body must both accept a leading parameter and return a value of this type {@code V}. |
| * <li>If {@code init} is non-{@code null}, it must have return type {@code V}. |
| * Its parameter list (of some <a href="MethodHandles.html#astar">form {@code (A*)}</a>) must be |
| * <a href="MethodHandles.html#effid">effectively identical</a> |
| * to the external parameter list {@code (A...)}. |
| * <li>If {@code init} is {@code null}, the loop variable will be initialized to its |
| * {@linkplain #empty default value}. |
| * <li>If the {@code iterator} handle is non-{@code null}, it must have the return |
| * type {@code java.util.Iterator} or a subtype thereof. |
| * The iterator it produces when the loop is executed will be assumed |
| * to yield values which can be converted to type {@code T}. |
| * <li>The parameter list of an {@code iterator} that is non-{@code null} (of some form {@code (A*)}) must be |
| * effectively identical to the external parameter list {@code (A...)}. |
| * <li>If {@code iterator} is {@code null} it defaults to a method handle which behaves |
| * like {@link java.lang.Iterable#iterator()}. In that case, the internal parameter list |
| * {@code (V T A...)} must have at least one {@code A} type, and the default iterator |
| * handle parameter is adjusted to accept the leading {@code A} type, as if by |
| * the {@link MethodHandle#asType asType} conversion method. |
| * The leading {@code A} type must be {@code Iterable} or a subtype thereof. |
| * This conversion step, done at loop construction time, must not throw a {@code WrongMethodTypeException}. |
| * </ul> |
| * <p> |
| * The type {@code T} may be either a primitive or reference. |
| * Since type {@code Iterator<T>} is erased in the method handle representation to the raw type {@code Iterator}, |
| * the {@code iteratedLoop} combinator adjusts the leading argument type for {@code body} to {@code Object} |
| * as if by the {@link MethodHandle#asType asType} conversion method. |
| * Therefore, if an iterator of the wrong type appears as the loop is executed, runtime exceptions may occur |
| * as the result of dynamic conversions performed by {@link MethodHandle#asType(MethodType)}. |
| * <p> |
| * The resulting loop handle's result type and parameter signature are determined as follows:<ul> |
| * <li>The loop handle's result type is the result type {@code V} of the body. |
| * <li>The loop handle's parameter types are the types {@code (A...)}, |
| * from the external parameter list. |
| * </ul> |
| * <p> |
| * Here is pseudocode for the resulting loop handle. In the code, {@code V}/{@code v} represent the type / value of |
| * the loop variable as well as the result type of the loop; {@code T}/{@code t}, that of the elements of the |
| * structure the loop iterates over, and {@code A...}/{@code a...} represent arguments passed to the loop. |
| * <blockquote><pre>{@code |
| * Iterator<T> iterator(A...); // defaults to Iterable::iterator |
| * V init(A...); |
| * V body(V,T,A...); |
| * V iteratedLoop(A... a...) { |
| * Iterator<T> it = iterator(a...); |
| * V v = init(a...); |
| * while (it.hasNext()) { |
| * T t = it.next(); |
| * v = body(v, t, a...); |
| * } |
| * return v; |
| * } |
| * }</pre></blockquote> |
| * |
| * @apiNote Example: |
| * <blockquote><pre>{@code |
| * // get an iterator from a list |
| * static List<String> reverseStep(List<String> r, String e) { |
| * r.add(0, e); |
| * return r; |
| * } |
| * static List<String> newArrayList() { return new ArrayList<>(); } |
| * // assume MH_reverseStep and MH_newArrayList are handles to the above methods |
| * MethodHandle loop = MethodHandles.iteratedLoop(null, MH_newArrayList, MH_reverseStep); |
| * List<String> list = Arrays.asList("a", "b", "c", "d", "e"); |
| * List<String> reversedList = Arrays.asList("e", "d", "c", "b", "a"); |
| * assertEquals(reversedList, (List<String>) loop.invoke(list)); |
| * }</pre></blockquote> |
| * |
| * @apiNote The implementation of this method can be expressed approximately as follows: |
| * <blockquote><pre>{@code |
| * MethodHandle iteratedLoop(MethodHandle iterator, MethodHandle init, MethodHandle body) { |
| * // assume MH_next, MH_hasNext, MH_startIter are handles to methods of Iterator/Iterable |
| * Class<?> returnType = body.type().returnType(); |
| * Class<?> ttype = body.type().parameterType(returnType == void.class ? 0 : 1); |
| * MethodHandle nextVal = MH_next.asType(MH_next.type().changeReturnType(ttype)); |
| * MethodHandle retv = null, step = body, startIter = iterator; |
| * if (returnType != void.class) { |
| * // the simple thing first: in (I V A...), drop the I to get V |
| * retv = dropArguments(identity(returnType), 0, Iterator.class); |
| * // body type signature (V T A...), internal loop types (I V A...) |
| * step = swapArguments(body, 0, 1); // swap V <-> T |
| * } |
| * if (startIter == null) startIter = MH_getIter; |
| * MethodHandle[] |
| * iterVar = { startIter, null, MH_hasNext, retv }, // it = iterator; while (it.hasNext()) |
| * bodyClause = { init, filterArguments(step, 0, nextVal) }; // v = body(v, t, a) |
| * return loop(iterVar, bodyClause); |
| * } |
| * }</pre></blockquote> |
| * |
| * @param iterator an optional handle to return the iterator to start the loop. |
| * If non-{@code null}, the handle must return {@link java.util.Iterator} or a subtype. |
| * See above for other constraints. |
| * @param init optional initializer, providing the initial value of the loop variable. |
| * May be {@code null}, implying a default initial value. See above for other constraints. |
| * @param body body of the loop, which may not be {@code null}. |
| * It controls the loop parameters and result type in the standard case (see above for details). |
| * It must accept its own return type (if non-void) plus a {@code T} parameter (for the iterated values), |
| * and may accept any number of additional types. |
| * See above for other constraints. |
| * |
| * @return a method handle embodying the iteration loop functionality. |
| * @throws NullPointerException if the {@code body} handle is {@code null}. |
| * @throws IllegalArgumentException if any argument violates the above requirements. |
| * |
| * @since 9 |
| */ |
| public static MethodHandle iteratedLoop(MethodHandle iterator, MethodHandle init, MethodHandle body) { |
| Class<?> iterableType = iteratedLoopChecks(iterator, init, body); |
| Class<?> returnType = body.type().returnType(); |
| // Android-changed: getConstantHandle is in MethodHandles. |
| // MethodHandle hasNext = MethodHandleImpl.getConstantHandle(MethodHandleImpl.MH_iteratePred); |
| // MethodHandle nextRaw = MethodHandleImpl.getConstantHandle(MethodHandleImpl.MH_iterateNext); |
| MethodHandle hasNext = getConstantHandle(MH_iteratePred); |
| MethodHandle nextRaw = getConstantHandle(MH_iterateNext); |
| MethodHandle startIter; |
| MethodHandle nextVal; |
| { |
| MethodType iteratorType; |
| if (iterator == null) { |
| // derive argument type from body, if available, else use Iterable |
| // Android-changed: getConstantHandle is in MethodHandles. |
| // startIter = MethodHandleImpl.getConstantHandle(MethodHandleImpl.MH_initIterator); |
| startIter = getConstantHandle(MH_initIterator); |
| iteratorType = startIter.type().changeParameterType(0, iterableType); |
| } else { |
| // force return type to the internal iterator class |
| iteratorType = iterator.type().changeReturnType(Iterator.class); |
| startIter = iterator; |
| } |
| Class<?> ttype = body.type().parameterType(returnType == void.class ? 0 : 1); |
| MethodType nextValType = nextRaw.type().changeReturnType(ttype); |
| |
| // perform the asType transforms under an exception transformer, as per spec.: |
| try { |
| startIter = startIter.asType(iteratorType); |
| nextVal = nextRaw.asType(nextValType); |
| } catch (WrongMethodTypeException ex) { |
| throw new IllegalArgumentException(ex); |
| } |
| } |
| |
| MethodHandle retv = null, step = body; |
| if (returnType != void.class) { |
| // the simple thing first: in (I V A...), drop the I to get V |
| retv = dropArguments(identity(returnType), 0, Iterator.class); |
| // body type signature (V T A...), internal loop types (I V A...) |
| step = swapArguments(body, 0, 1); // swap V <-> T |
| } |
| |
| MethodHandle[] |
| iterVar = { startIter, null, hasNext, retv }, |
| bodyClause = { init, filterArgument(step, 0, nextVal) }; |
| return loop(iterVar, bodyClause); |
| } |
| |
| private static Class<?> iteratedLoopChecks(MethodHandle iterator, MethodHandle init, MethodHandle body) { |
| Objects.requireNonNull(body); |
| MethodType bodyType = body.type(); |
| Class<?> returnType = bodyType.returnType(); |
| List<Class<?>> internalParamList = bodyType.parameterList(); |
| // strip leading V value if present |
| int vsize = (returnType == void.class ? 0 : 1); |
| if (vsize != 0 && (internalParamList.size() == 0 || internalParamList.get(0) != returnType)) { |
| // argument list has no "V" => error |
| MethodType expected = bodyType.insertParameterTypes(0, returnType); |
| throw misMatchedTypes("body function", bodyType, expected); |
| } else if (internalParamList.size() <= vsize) { |
| // missing T type => error |
| MethodType expected = bodyType.insertParameterTypes(vsize, Object.class); |
| throw misMatchedTypes("body function", bodyType, expected); |
| } |
| List<Class<?>> externalParamList = internalParamList.subList(vsize + 1, internalParamList.size()); |
| Class<?> iterableType = null; |
| if (iterator != null) { |
| // special case; if the body handle only declares V and T then |
| // the external parameter list is obtained from iterator handle |
| if (externalParamList.isEmpty()) { |
| externalParamList = iterator.type().parameterList(); |
| } |
| MethodType itype = iterator.type(); |
| if (!Iterator.class.isAssignableFrom(itype.returnType())) { |
| throw newIllegalArgumentException("iteratedLoop first argument must have Iterator return type"); |
| } |
| if (!itype.effectivelyIdenticalParameters(0, externalParamList)) { |
| MethodType expected = methodType(itype.returnType(), externalParamList); |
| throw misMatchedTypes("iterator parameters", itype, expected); |
| } |
| } else { |
| if (externalParamList.isEmpty()) { |
| // special case; if the iterator handle is null and the body handle |
| // only declares V and T then the external parameter list consists |
| // of Iterable |
| externalParamList = Arrays.asList(Iterable.class); |
| iterableType = Iterable.class; |
| } else { |
| // special case; if the iterator handle is null and the external |
| // parameter list is not empty then the first parameter must be |
| // assignable to Iterable |
| iterableType = externalParamList.get(0); |
| if (!Iterable.class.isAssignableFrom(iterableType)) { |
| throw newIllegalArgumentException( |
| "inferred first loop argument must inherit from Iterable: " + iterableType); |
| } |
| } |
| } |
| if (init != null) { |
| MethodType initType = init.type(); |
| if (initType.returnType() != returnType || |
| !initType.effectivelyIdenticalParameters(0, externalParamList)) { |
| throw misMatchedTypes("loop initializer", initType, methodType(returnType, externalParamList)); |
| } |
| } |
| return iterableType; // help the caller a bit |
| } |
| |
| /*non-public*/ static MethodHandle swapArguments(MethodHandle mh, int i, int j) { |
| // there should be a better way to uncross my wires |
| int arity = mh.type().parameterCount(); |
| int[] order = new int[arity]; |
| for (int k = 0; k < arity; k++) order[k] = k; |
| order[i] = j; order[j] = i; |
| Class<?>[] types = mh.type().parameterArray(); |
| Class<?> ti = types[i]; types[i] = types[j]; types[j] = ti; |
| MethodType swapType = methodType(mh.type().returnType(), types); |
| return permuteArguments(mh, swapType, order); |
| } |
| |
| /** |
| * Makes a method handle that adapts a {@code target} method handle by wrapping it in a {@code try-finally} block. |
| * Another method handle, {@code cleanup}, represents the functionality of the {@code finally} block. Any exception |
| * thrown during the execution of the {@code target} handle will be passed to the {@code cleanup} handle. The |
| * exception will be rethrown, unless {@code cleanup} handle throws an exception first. The |
| * value returned from the {@code cleanup} handle's execution will be the result of the execution of the |
| * {@code try-finally} handle. |
| * <p> |
| * The {@code cleanup} handle will be passed one or two additional leading arguments. |
| * The first is the exception thrown during the |
| * execution of the {@code target} handle, or {@code null} if no exception was thrown. |
| * The second is the result of the execution of the {@code target} handle, or, if it throws an exception, |
| * a {@code null}, zero, or {@code false} value of the required type is supplied as a placeholder. |
| * The second argument is not present if the {@code target} handle has a {@code void} return type. |
| * (Note that, except for argument type conversions, combinators represent {@code void} values in parameter lists |
| * by omitting the corresponding paradoxical arguments, not by inserting {@code null} or zero values.) |
| * <p> |
| * The {@code target} and {@code cleanup} handles must have the same corresponding argument and return types, except |
| * that the {@code cleanup} handle may omit trailing arguments. Also, the {@code cleanup} handle must have one or |
| * two extra leading parameters:<ul> |
| * <li>a {@code Throwable}, which will carry the exception thrown by the {@code target} handle (if any); and |
| * <li>a parameter of the same type as the return type of both {@code target} and {@code cleanup}, which will carry |
| * the result from the execution of the {@code target} handle. |
| * This parameter is not present if the {@code target} returns {@code void}. |
| * </ul> |
| * <p> |
| * The pseudocode for the resulting adapter looks as follows. In the code, {@code V} represents the result type of |
| * the {@code try/finally} construct; {@code A}/{@code a}, the types and values of arguments to the resulting |
| * handle consumed by the cleanup; and {@code B}/{@code b}, those of arguments to the resulting handle discarded by |
| * the cleanup. |
| * <blockquote><pre>{@code |
| * V target(A..., B...); |
| * V cleanup(Throwable, V, A...); |
| * V adapter(A... a, B... b) { |
| * V result = (zero value for V); |
| * Throwable throwable = null; |
| * try { |
| * result = target(a..., b...); |
| * } catch (Throwable t) { |
| * throwable = t; |
| * throw t; |
| * } finally { |
| * result = cleanup(throwable, result, a...); |
| * } |
| * return result; |
| * } |
| * }</pre></blockquote> |
| * <p> |
| * Note that the saved arguments ({@code a...} in the pseudocode) cannot |
| * be modified by execution of the target, and so are passed unchanged |
| * from the caller to the cleanup, if it is invoked. |
| * <p> |
| * The target and cleanup must return the same type, even if the cleanup |
| * always throws. |
| * To create such a throwing cleanup, compose the cleanup logic |
| * with {@link #throwException throwException}, |
| * in order to create a method handle of the correct return type. |
| * <p> |
| * Note that {@code tryFinally} never converts exceptions into normal returns. |
| * In rare cases where exceptions must be converted in that way, first wrap |
| * the target with {@link #catchException(MethodHandle, Class, MethodHandle)} |
| * to capture an outgoing exception, and then wrap with {@code tryFinally}. |
| * <p> |
| * It is recommended that the first parameter type of {@code cleanup} be |
| * declared {@code Throwable} rather than a narrower subtype. This ensures |
| * {@code cleanup} will always be invoked with whatever exception that |
| * {@code target} throws. Declaring a narrower type may result in a |
| * {@code ClassCastException} being thrown by the {@code try-finally} |
| * handle if the type of the exception thrown by {@code target} is not |
| * assignable to the first parameter type of {@code cleanup}. Note that |
| * various exception types of {@code VirtualMachineError}, |
| * {@code LinkageError}, and {@code RuntimeException} can in principle be |
| * thrown by almost any kind of Java code, and a finally clause that |
| * catches (say) only {@code IOException} would mask any of the others |
| * behind a {@code ClassCastException}. |
| * |
| * @param target the handle whose execution is to be wrapped in a {@code try} block. |
| * @param cleanup the handle that is invoked in the finally block. |
| * |
| * @return a method handle embodying the {@code try-finally} block composed of the two arguments. |
| * @throws NullPointerException if any argument is null |
| * @throws IllegalArgumentException if {@code cleanup} does not accept |
| * the required leading arguments, or if the method handle types do |
| * not match in their return types and their |
| * corresponding trailing parameters |
| * |
| * @see MethodHandles#catchException(MethodHandle, Class, MethodHandle) |
| * @since 9 |
| */ |
| public static MethodHandle tryFinally(MethodHandle target, MethodHandle cleanup) { |
| List<Class<?>> targetParamTypes = target.type().parameterList(); |
| Class<?> rtype = target.type().returnType(); |
| |
| tryFinallyChecks(target, cleanup); |
| |
| // Match parameter lists: if the cleanup has a shorter parameter list than the target, add ignored arguments. |
| // The cleanup parameter list (minus the leading Throwable and result parameters) must be a sublist of the |
| // target parameter list. |
| cleanup = dropArgumentsToMatch(cleanup, (rtype == void.class ? 1 : 2), targetParamTypes, 0); |
| |
| // Ensure that the intrinsic type checks the instance thrown by the |
| // target against the first parameter of cleanup |
| cleanup = cleanup.asType(cleanup.type().changeParameterType(0, Throwable.class)); |
| |
| // Use asFixedArity() to avoid unnecessary boxing of last argument for VarargsCollector case. |
| // Android-changed: use Transformer implementation. |
| // return MethodHandleImpl.makeTryFinally(target.asFixedArity(), cleanup.asFixedArity(), rtype, targetParamTypes); |
| return new Transformers.TryFinally(target.asFixedArity(), cleanup.asFixedArity()); |
| } |
| |
| private static void tryFinallyChecks(MethodHandle target, MethodHandle cleanup) { |
| Class<?> rtype = target.type().returnType(); |
| if (rtype != cleanup.type().returnType()) { |
| throw misMatchedTypes("target and return types", cleanup.type().returnType(), rtype); |
| } |
| MethodType cleanupType = cleanup.type(); |
| if (!Throwable.class.isAssignableFrom(cleanupType.parameterType(0))) { |
| throw misMatchedTypes("cleanup first argument and Throwable", cleanup.type(), Throwable.class); |
| } |
| if (rtype != void.class && cleanupType.parameterType(1) != rtype) { |
| throw misMatchedTypes("cleanup second argument and target return type", cleanup.type(), rtype); |
| } |
| // The cleanup parameter list (minus the leading Throwable and result parameters) must be a sublist of the |
| // target parameter list. |
| int cleanupArgIndex = rtype == void.class ? 1 : 2; |
| if (!cleanupType.effectivelyIdenticalParameters(cleanupArgIndex, target.type().parameterList())) { |
| throw misMatchedTypes("cleanup parameters after (Throwable,result) and target parameter list prefix", |
| cleanup.type(), target.type()); |
| } |
| } |
| |
| /** |
| * Creates a table switch method handle, which can be used to switch over a set of target |
| * method handles, based on a given target index, called selector. |
| * <p> |
| * For a selector value of {@code n}, where {@code n} falls in the range {@code [0, N)}, |
| * and where {@code N} is the number of target method handles, the table switch method |
| * handle will invoke the n-th target method handle from the list of target method handles. |
| * <p> |
| * For a selector value that does not fall in the range {@code [0, N)}, the table switch |
| * method handle will invoke the given fallback method handle. |
| * <p> |
| * All method handles passed to this method must have the same type, with the additional |
| * requirement that the leading parameter be of type {@code int}. The leading parameter |
| * represents the selector. |
| * <p> |
| * Any trailing parameters present in the type will appear on the returned table switch |
| * method handle as well. Any arguments assigned to these parameters will be forwarded, |
| * together with the selector value, to the selected method handle when invoking it. |
| * |
| * @apiNote Example: |
| * The cases each drop the {@code selector} value they are given, and take an additional |
| * {@code String} argument, which is concatenated (using {@link String#concat(String)}) |
| * to a specific constant label string for each case: |
| * <blockquote><pre>{@code |
| * MethodHandles.Lookup lookup = MethodHandles.lookup(); |
| * MethodHandle caseMh = lookup.findVirtual(String.class, "concat", |
| * MethodType.methodType(String.class, String.class)); |
| * caseMh = MethodHandles.dropArguments(caseMh, 0, int.class); |
| * |
| * MethodHandle caseDefault = MethodHandles.insertArguments(caseMh, 1, "default: "); |
| * MethodHandle case0 = MethodHandles.insertArguments(caseMh, 1, "case 0: "); |
| * MethodHandle case1 = MethodHandles.insertArguments(caseMh, 1, "case 1: "); |
| * |
| * MethodHandle mhSwitch = MethodHandles.tableSwitch( |
| * caseDefault, |
| * case0, |
| * case1 |
| * ); |
| * |
| * assertEquals("default: data", (String) mhSwitch.invokeExact(-1, "data")); |
| * assertEquals("case 0: data", (String) mhSwitch.invokeExact(0, "data")); |
| * assertEquals("case 1: data", (String) mhSwitch.invokeExact(1, "data")); |
| * assertEquals("default: data", (String) mhSwitch.invokeExact(2, "data")); |
| * }</pre></blockquote> |
| * |
| * @param fallback the fallback method handle that is called when the selector is not |
| * within the range {@code [0, N)}. |
| * @param targets array of target method handles. |
| * @return the table switch method handle. |
| * @throws NullPointerException if {@code fallback}, the {@code targets} array, or any |
| * any of the elements of the {@code targets} array are |
| * {@code null}. |
| * @throws IllegalArgumentException if the {@code targets} array is empty, if the leading |
| * parameter of the fallback handle or any of the target |
| * handles is not {@code int}, or if the types of |
| * the fallback handle and all of target handles are |
| * not the same. |
| */ |
| public static MethodHandle tableSwitch(MethodHandle fallback, MethodHandle... targets) { |
| Objects.requireNonNull(fallback); |
| Objects.requireNonNull(targets); |
| targets = targets.clone(); |
| MethodType type = tableSwitchChecks(fallback, targets); |
| // Android-changed: use a Transformer for the implementation. |
| // return MethodHandleImpl.makeTableSwitch(type, fallback, targets); |
| return new Transformers.TableSwitch(type, fallback, targets); |
| } |
| |
| private static MethodType tableSwitchChecks(MethodHandle defaultCase, MethodHandle[] caseActions) { |
| if (caseActions.length == 0) |
| throw new IllegalArgumentException("Not enough cases: " + Arrays.toString(caseActions)); |
| |
| MethodType expectedType = defaultCase.type(); |
| |
| if (!(expectedType.parameterCount() >= 1) || expectedType.parameterType(0) != int.class) |
| throw new IllegalArgumentException( |
| "Case actions must have int as leading parameter: " + Arrays.toString(caseActions)); |
| |
| for (MethodHandle mh : caseActions) { |
| Objects.requireNonNull(mh); |
| // Android-changed: MethodType's not interned. |
| // if (mh.type() != expectedType) |
| if (!mh.type().equals(expectedType)) |
| throw new IllegalArgumentException( |
| "Case actions must have the same type: " + Arrays.toString(caseActions)); |
| } |
| |
| return expectedType; |
| } |
| |
| // BEGIN Android-added: Code from OpenJDK's MethodHandleImpl. |
| |
| /** |
| * This method is bound as the predicate in {@linkplain MethodHandles#countedLoop(MethodHandle, MethodHandle, |
| * MethodHandle) counting loops}. |
| * |
| * @param limit the upper bound of the parameter, statically bound at loop creation time. |
| * @param counter the counter parameter, passed in during loop execution. |
| * |
| * @return whether the counter has reached the limit. |
| * @hide |
| */ |
| public static boolean countedLoopPredicate(int limit, int counter) { |
| return counter < limit; |
| } |
| |
| /** |
| * This method is bound as the step function in {@linkplain MethodHandles#countedLoop(MethodHandle, MethodHandle, |
| * MethodHandle) counting loops} to increment the counter. |
| * |
| * @param limit the upper bound of the loop counter (ignored). |
| * @param counter the loop counter. |
| * |
| * @return the loop counter incremented by 1. |
| * @hide |
| */ |
| public static int countedLoopStep(int limit, int counter) { |
| return counter + 1; |
| } |
| |
| /** |
| * This is bound to initialize the loop-local iterator in {@linkplain MethodHandles#iteratedLoop iterating loops}. |
| * |
| * @param it the {@link Iterable} over which the loop iterates. |
| * |
| * @return an {@link Iterator} over the argument's elements. |
| * @hide |
| */ |
| public static Iterator<?> initIterator(Iterable<?> it) { |
| return it.iterator(); |
| } |
| |
| /** |
| * This method is bound as the predicate in {@linkplain MethodHandles#iteratedLoop iterating loops}. |
| * |
| * @param it the iterator to be checked. |
| * |
| * @return {@code true} iff there are more elements to iterate over. |
| * @hide |
| */ |
| public static boolean iteratePredicate(Iterator<?> it) { |
| return it.hasNext(); |
| } |
| |
| /** |
| * This method is bound as the step for retrieving the current value from the iterator in {@linkplain |
| * MethodHandles#iteratedLoop iterating loops}. |
| * |
| * @param it the iterator. |
| * |
| * @return the next element from the iterator. |
| * @hide |
| */ |
| public static Object iterateNext(Iterator<?> it) { |
| return it.next(); |
| } |
| |
| // Indexes into constant method handles: |
| static final int |
| MH_cast = 0, |
| MH_selectAlternative = 1, |
| MH_copyAsPrimitiveArray = 2, |
| MH_fillNewTypedArray = 3, |
| MH_fillNewArray = 4, |
| MH_arrayIdentity = 5, |
| MH_countedLoopPred = 6, |
| MH_countedLoopStep = 7, |
| MH_initIterator = 8, |
| MH_iteratePred = 9, |
| MH_iterateNext = 10, |
| MH_Array_newInstance = 11, |
| MH_LIMIT = 12; |
| |
| static MethodHandle getConstantHandle(int idx) { |
| MethodHandle handle = HANDLES[idx]; |
| if (handle != null) { |
| return handle; |
| } |
| return setCachedHandle(idx, makeConstantHandle(idx)); |
| } |
| |
| private static synchronized MethodHandle setCachedHandle(int idx, final MethodHandle method) { |
| // Simulate a CAS, to avoid racy duplication of results. |
| MethodHandle prev = HANDLES[idx]; |
| if (prev != null) { |
| return prev; |
| } |
| HANDLES[idx] = method; |
| return method; |
| } |
| |
| // Local constant method handles: |
| private static final @Stable MethodHandle[] HANDLES = new MethodHandle[MH_LIMIT]; |
| |
| private static MethodHandle makeConstantHandle(int idx) { |
| try { |
| // Android-added: local IMPL_LOOKUP. |
| final Lookup IMPL_LOOKUP = MethodHandles.Lookup.IMPL_LOOKUP; |
| switch (idx) { |
| // Android-removed: not-used. |
| /* |
| case MH_cast: |
| return IMPL_LOOKUP.findVirtual(Class.class, "cast", |
| MethodType.methodType(Object.class, Object.class)); |
| case MH_copyAsPrimitiveArray: |
| return IMPL_LOOKUP.findStatic(MethodHandleImpl.class, "copyAsPrimitiveArray", |
| MethodType.methodType(Object.class, Wrapper.class, Object[].class)); |
| case MH_arrayIdentity: |
| return IMPL_LOOKUP.findStatic(MethodHandleImpl.class, "identity", |
| MethodType.methodType(Object[].class, Object[].class)); |
| case MH_fillNewArray: |
| return IMPL_LOOKUP.findStatic(MethodHandleImpl.class, "fillNewArray", |
| MethodType.methodType(Object[].class, Integer.class, Object[].class)); |
| case MH_fillNewTypedArray: |
| return IMPL_LOOKUP.findStatic(MethodHandleImpl.class, "fillNewTypedArray", |
| MethodType.methodType(Object[].class, Object[].class, Integer.class, Object[].class)); |
| case MH_selectAlternative: |
| return IMPL_LOOKUP.findStatic(MethodHandleImpl.class, "selectAlternative", |
| MethodType.methodType(MethodHandle.class, boolean.class, MethodHandle.class, MethodHandle.class)); |
| */ |
| case MH_countedLoopPred: |
| // Android-changed: methods moved to this file. |
| // return IMPL_LOOKUP.findStatic(MethodHandleImpl.class, "countedLoopPredicate", |
| // MethodType.methodType(boolean.class, int.class, int.class)); |
| return IMPL_LOOKUP.findStatic(MethodHandles.class, "countedLoopPredicate", |
| MethodType.methodType(boolean.class, int.class, int.class)); |
| case MH_countedLoopStep: |
| // Android-changed: methods moved to this file. |
| // return IMPL_LOOKUP.findStatic(MethodHandleImpl.class, "countedLoopStep", |
| // MethodType.methodType(int.class, int.class, int.class)); |
| return IMPL_LOOKUP.findStatic(MethodHandles.class, "countedLoopStep", |
| MethodType.methodType(int.class, int.class, int.class)); |
| case MH_initIterator: |
| // Android-changed: methods moved to this file. |
| // return IMPL_LOOKUP.findStatic(MethodHandleImpl.class, "initIterator", |
| // MethodType.methodType(Iterator.class, Iterable.class)); |
| return IMPL_LOOKUP.findStatic(MethodHandles.class, "initIterator", |
| MethodType.methodType(Iterator.class, Iterable.class)); |
| case MH_iteratePred: |
| // Android-changed: methods moved to this file. |
| // return IMPL_LOOKUP.findStatic(MethodHandleImpl.class, "iteratePredicate", |
| // MethodType.methodType(boolean.class, Iterator.class)); |
| return IMPL_LOOKUP.findStatic(MethodHandles.class, "iteratePredicate", |
| MethodType.methodType(boolean.class, Iterator.class)); |
| case MH_iterateNext: |
| // Android-changed: methods moved to this file. |
| // return IMPL_LOOKUP.findStatic(MethodHandleImpl.class, "iterateNext", |
| // MethodType.methodType(Object.class, Iterator.class)); |
| return IMPL_LOOKUP.findStatic(MethodHandles.class, "iterateNext", |
| MethodType.methodType(Object.class, Iterator.class)); |
| // Android-removed: not-used. |
| /* |
| case MH_Array_newInstance: |
| return IMPL_LOOKUP.findStatic(Array.class, "newInstance", |
| MethodType.methodType(Object.class, Class.class, int.class)); |
| */ |
| } |
| } catch (ReflectiveOperationException ex) { |
| throw newInternalError(ex); |
| } |
| |
| throw newInternalError("Unknown function index: " + idx); |
| } |
| // END Android-added: Code from OpenJDK's MethodHandleImpl. |
| } |
